LIBRARY OF CONGRESS. 



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UNITED STATES OF AMERICA. 



STATIONARY 

Steam Engines 

Simple and Compound; 



ESPECIALLY AS ADAPTED TO 



ELECTRIC LIGHTING PURPOSES. 



By ROBERT H. THURSTON, A.M., LL.D., Dr.Eng'g, 

\\ 

Formerly of the U.S.N. Engineer Corps ; Director of Sibley College, Cornell 

University ; Past President American Society Mechanical Engineers ; 

Member American Society Civil Engineers; American 

Institute Mining Engineers, Etc. 



FOURTH EDITION. 



REVISED WITH ADDITIONS, 




Sew**: ^ 

JOHN WILEY & SONS, 
53 E. 10th Street. 

1890. 






Tb~| 



Copyright, 1883, Electrician. 



Copyright, 1884, R. H. Thurston. 



Copyright, 1890, R. H. Thurston. 



Press of J. J. Little & Co. 
Astor Place, New York. 



v/ 



PREFACE TO THE FOURTH EDITION. 



THIS little book is composed of articles written by the 
author for the Electrical Engineer, supplemented by 
later revision, and by the addition of matter relating to the 
now familiar " compound " engine, which had been origi- 
nally prepared for the lecture-room and subsequently pre- 
sented in abstract to the American Society of Mechanical 
Engineers. It had its origin in a request, by the editor of 
the periodical above mentioned, that the readers of that 
journal be given an account, in simple and concise but 
fairly complete form, of the various types of steam-engine 
in common use ; of the principles of their design ; the cir- 
cumstances determining their efficiencies and their economy 
of steam and fuel ; their various forms as usually built, and 
the best methods of insuring further improvement. 

In complying with this demand, it has been thought 
advisable to give a brief outline of the progress of discovery 
and invention, from the earliest days of application of steam 
to the production and utilization of mechanical energy ; to 
trace the steps which led up from the rude devices of 
Savery and Newcomen to the highest attainments of the 
engineer of to-day ; next, to exhibit the principles of 



iv PREFACE. 



economy in the efficient application, through the operation 
of the steam-engine, of heat-energy into mechanical power, 
by conversion of the one form of energy into the other, 
observing the causes and methods of waste and the means 
available for their reduction, if not for their extinction, in 
some directions ; and finally, to describe and illustrate the 
standard types of engine to-day in use, and the details, so 
far as may seem important, of their construction. 

The peculiar demands made upon the designing and 
constructing engineer in later years by the introduction 
of electric lighting, with its requirements of economical 
operation of machinery having very high speed of rotation 
and absolutely compelling exact regulation, has led to the 
invention of new forms of engine, and especially of new 
methods of steam distribution and regulation. This has 
resulted in the introduction, in turn, of a new class of 
engines, known to the profession and in the trade as 
"high-speed engines,'' which possess these essential quali- 
fications of great velocity of rotation, and of nicety of regu- 
lation in a superlative degree, and which have, by their 
sharp competition with the older types, in their turn com- 
pelled an unexampled improvement in the latter, in the 
endeavor, largely successful, to adapt them to the same pur- 
pose. Thus high speed, very perfect regulation and very 
smooth action at maximum speeds, have come to character- 
ize the steam-engine of the present time in far greater 
degree than ever before ; while modern systems of manu- 
facture and the extensive application of special tools, 
designed each for its special work, have reduced costs of 
production of this right arm of civilization to such an extent 



PREFACE. 



as to insure a more rapid progress in the useful arts than 
has ever yet been seen. 

This subject was deemed so important to the mechanical 
engineer and to all having anything to do with the remark- 
able expansion now occurring in the work of electric light- 
ing, and of the extension of the systems of application of 
power, through the use of electricity to the impulsion of 
street railway cars and to the machinery of the smaller 
industries (to the supply of power to small shops and estab- 
lishments), that it was considered probable that a philo- 
sophical account of the rise and progress of this now enor- 
mous industry of steam-engine construction, and especially 
of its product, would be likely to prove acceptable to many 
intelligent readers outside as well as within the profession. 
In this anticipation the publishers have not been disap- 
pointed, as the fact of the sale of rapidly succeeding edi- 
tions proves to their satisfaction as well as to that of the 
author. 

The latest addition to this little work is the final chapter 
on the compound engine and the principles of its design, 
construction, and operation in successful competition with 
the older forms. The importance of this new departure in 
the construction of small engines, for electric lighting and 
similar purposes, may be imagined when it is noted that in 
some cases, at least, the compounding of a well-known type 
of " high-speed " engine has reduced its consumption of 
fuel for similar sizes and work enormously, the simple 
using almost double the amount of steam and fuel, in the 
smaller sizes, demanded by the compounded engine of 
otherwise exactly similar design and construction. As is 



VI PREFACE, 

stated in the text, the smaller the engine the greater is the 
original waste, the greater the margin for improvement, 
and the greater the gain to be anticipated by this change. 

The author has endeavored to do full justice to the vari- 
ous engines described, while carefully avoiding the expres- 
sion of merely personal opinion in reference to debatable 
points. 



CONTENTS. 



ART. PAGE 
I. — Historical Development of the Steam Engine 3 

II. — Principles of Economy ; Special requirements 9 

III. — Engines indirectly connected. 

The Corliss Engine 17 

The Wheelock Engine 32 

The Greene Engine 36 

IV. — Engines capable of direct connection. 

The Porter-Allen Engine 52 

" Buckeye " and Hartford Engines 69 

The Cummer Engine 82 

The " Straight-Line " Engine 97 

The Armington & Sims Engine 116 

V.— Fast Engines of peculiar design. 

The Ball Engine. 156 

The Ide Engine 148 

N. Y. Safety Steam Power Co • 155 

Ericsson and Westinghouse Engines 162 

VI. — Latest Changes ; Compound Engines 177 



Steam Engines 

FOR ELECTRIC LIGHTING PLANTS. 



i. 

Historical— The Development of the Steam Engine. 

r I ^HE growth of the steam engine into the forms now 
-*- familiar to everyone who takes the slightest interest 
in this most important of modern mechanisms, has occurred 
by a series of transitions which is easily traced, and which 
is especially interesting to every thoughtful mechanic as 
representing the steps in a steady progression, toward ideal 
perfection, of which the end is not yet seen. 

A century ago, James Watt had just begun to introduce 
the first engines belonging to a, then, new type. 1 A century 
before (1698), the ingenuity and practical skill of Captain 
Savery, had conferred an enormous benefit upon the mining 
industries, and through them upon the world, by applying 
the "fire engine" of the Marquis of Worcester to raising 
water from the then rapidly deepening mines. 2 Savery used 
steam of 8 to 10 atmospheres (120 to 150 pounds) total 
pressure, in some cases,and he is entitled to fame as the first to 
introduce that now familiar concomitant of civilization, the 

1. History of the Growth of the Steam Engine. International Series. N. Y., 
D. Appleton & Co. 

2. The writer finds this engine described in Harris's "Lexicon Technicum" of 
1704, of which, now rare work, he is so fortunate as to possess a copy. 



STEAM ENGINES FOR 



steam boiler explosion. The usual pressure was 3 atmos- 
pheres. These engines demanded about 30 pounds of coal, 
per horse-power per hour, as a minimum. The apparatus 
of Savery was not what would to-day be called a steam 
engine, at all. It was not a train of mechanism, involving 
moving parts, cylinder, piston, crank and fly-wheel, but 
either a single pair of closed vessels, or three vessels, one of 
which was a boiler, and the other, or others, metal chambers 
of spherical, cylindrical, or ellipsoidal form, which were at 
once condensers and pumps. The latter were filled with 
steam, which being condensed, the water rose into, and 
filled them, and was then forced out by a succeeding charge 
of steam, of pressure exceeding that of the head against 
which the lift took place. Huyghens (1680), and Papin 
(1690), proposed true engines with steam pistons traversing 
their cylinders, and forming, on the whole, much such a 
train of mechanism as is now so well known 3 ; but the 
Newcomen engine was the first of this type to come into 
practical use. This machine, then called the " Atmospheric 
Steam Engine," consisted of a steam cylinder, with a piston 
taking steam beneath, the upper end of the cylinder being 
open to the atmosphere, the piston actuating a " working 
beam," or " walking beam," and, through the latter, work- 
ing pumps attached to the opposite end. Neither crank, 
shaft, nor fly-wheel was used ; the action of the engine was 
controlled entirely by the adjustment of its valves. In its 
operation, steam at a little higher than atmospheric pressure, 
was admitted below the piston ; the weight at the pump end 
depressed that extremity of the beam, raising the piston. 

3. Mem. Acad. Sci. Paris, 1680. Acta Eruditorum. Leipsic, 1690. 



ELECTRIC LIGHTING PLANTS. 



The steam below the piston was then condensed by a jet 
of water thrown into the cylinder, producing a vacuum; and 
atmospheric pressure finally forced the piston down, rais- 
ing the pump-rod and plungers. The weight on the latter 
was adjusted to the work, so that, when steam was admitted, 
this weight should force the pumps to discharge the water. 
The only function of the steam was the displacement of the 
atmosphere, or counterbalancing it, by entering below the 
piston, and thus permitting the formation of a vacuum. A 
writer of that time states 4 that " Mr. Newcomen's invention 
of the fire engine, enabled us to sink our mines to twice the 
depth we could formerly do, by any other machinery "; but 
" every fire engine of magnitude consumes ^3,000 worth of 
coal per annum." The coal consumption was, at best, about 
20 pounds per hour and per horse-power. Smeaton, the 
greatest civil engineer of his time, put up many of these 
engines in Holland and elsewhere, as well as in Great 
Britain ; some were 66 inches in diameter of cylinder, and 
8 to 9 feet stroke of piston. It was this engine that Watt 
found in operation, when he entered upon the stage. 

Watt was not simply a mechanic ; he was a real philoso- 
pher, and a truly scientific investigator. A model New- 
comen engine, having been brought to him to be repaired, 
he took advantage of the opportunity to study the principles 
of its construction, to ascertain its defects, and to devise 
proper remedies. He found that the sources of loss were 
the conductivity, and radiating power of the steam cylinder, 
the alternate heating and cooling of the metal at each stroke, 
the imperfect vacuum, and the wastes from boiler and 
4. MinercUogia Cornubiensis. Price. 1778. Appendix. 



STEAM ENGINES FOR 



steam pipes. To correct these defects, he clothed his 
boilers and steam pipes with non-conductors, sometimes 
even making boiler shells of wood. Smeaton had already 
covered the pistons and cylinder heads with wood. Watt 
made a small wooden steam cylinder, and obtained great 
economy ; he made a more practicable improvement, how- 
ever, when he devised the steam jacket. He attached a 
separate condenser to prevent the loss due to the introduc- 
tion of condensing water into the steam cylinder, closed the 
cylinder at the top, made the engine double-acting, and 
finally adapted the engine to drive machinery, fitting it with 
shaft and fly-wheel, throttle valve, and governor, and thus 
making the steam engine such as we see it to-day, in all es- 
sential particulars, not excepting the steam jacket, and the 
arrangement of its valve gear to secure economy by the 
expansion of the steam. His engine was substantially com- 
plete by the year 1784. 5 

Later changes have been a succession of refinements, 
and of developments in application. Stephenson, and his 
contemporaries, applied steam on railroads ; Stevens, Fitch, 
and Evans, and, finally, Fulton, in the United States, and 
Bell and others, in Europe, introduced steam navigation ; 
Sickels invented the "detachable" cut-off valve gear ; 
Corliss introduced the peculiar type of engine that has 
given him a world-wide fame, and so attached its governor as 
to determine the point of cut-off automatically, and thus to 
regulate the engine ; and, a little earlier, Robert L. and 
Francis B. Stevens designed the American river steamboat, 
and its beam engine, with so simple and effective a valve 



5. History of the Growth of the Steam Engine. P. 119. Farey on St. Engine. 



ELECTRIC LIGHTING PLANTS. 



gear that it remains, to-day, still standard. The compound 
engine, even, was brought oat by contemporaries of Watt, 
and thus every prominent feature and essential detail of 
the modern steam engine was introduced at, or before, the 
middle of the nineteenth century. 

Yet, practice has been steadily changing during the cen- 
tury, and the form and proportions of the steam engine, and 
the methods of steam distribution, have been undergoing 
constant changes. In the time of Watt, steam was worked 
at about 7 pounds pressure, per square inch, in stationary 
engines; they were always fitted with condenser and air- 
pump, and were slow in movement, and were, consequently, 
of small power in proportion to their size; they wasted heat 
and fuel to such an extent, as to demand 6 or 8 pounds of 
coal per horse-power and per hour. It is true that Wolff, 
in 1804, expanded 6 or 8 times, using higher steam and ob- 
tained the horse-power with 4 pounds of fuel per hour, and 
that John Stevens and Oliver Evans, in the United States, 
and Trevithick, in Great Britain, had already used still 
higher steam in non-condensing engines; but these examples 
simply illustrated the fact, now familiar to every student of 
philosophical history, as pictured by Draper, Buckle and 
Whewell, that isolated examples which lead standard practice 
by a half century or more, are to be observed during the 
growth of every art. Recognized standard practice is al- 
ways as conservative as it is permitted to be by trade com- 
petition, and usually changes very slowly. Principles may 
be discovered and understood, and a correct theory of de- 
sign and of practice may be made generally familiar, and 
often is, in a brief period; but the growth of application 



STEAM ENGINES FOR 



and the familiarizing of constructors and operatives with 
new mechanisms, and new methods of management, re- 
quires time, and is slow at best. Thus it has happened, 
that although the principles of steam engine economy were, 
in the main, well understood by James Watt, and some of 
his competitors, nearly a century ago, and have become 
well settled in later years, we are still far from a completely 
satisfactory solution of the problem, which, as stated by 
the writer elsewhere, may be enunciated thus: — r To con- 
struct a machine which shall, in the most perfect manner 
possible, convert the energy of heat into mechanical 
power, the heat being derived from the combustion of 
fuel, and steam being the receiver and conveyer of that 
heat" 



ELECTRIC LIGHTING PLANTS. 



II. 

Principles of Economy ; Special Requirements. 

THE principles of economical working, noted by James 
Watt, and plainly stated by him, were but slowly 
recognized by others, and the improvement of the steam 
engine was, for many years, correspondingly slow. The 
principles that must govern the engineer, in the attempt to 
secure highest efficiency, may be summarized thus: 

i. The greatest practicable range of commercially 
economical expansive working of steam must be adopted; 
the fluid must enter the cylinder at the highest admissible 
pressure, and must be expanded down to the minimum 
economical pressure at exhaust. 

2. The wastes of heat must be made the least possible; 
all loss of heat by conduction and radiation from the engine 
must be prevented, if possible, and the usually much more 
serious waste which occurs within the engine, by transfer 
of heat from the steam side to the exhaust, by "cylinder 
condensation " and re-evaporation, without doing its pro- 
portion of work, must be checked as completely as is 
practicable. This latter condition, as well as commercial 
considerations, limits the degree of expansion allowable. 
It also dictates high speed of engine. 

3. The largest amount of work must be done by the 
engine that it can perform, with due regard to the preced- 
ing conditions. This condition compels us to drive 'the 
engine up to the highest safe speed, and to adopt the high- 
est practicable mean steam pressure. 



STEAM ENGINES FOR 



The first two of the above requirements give maximum 
efficiency of fluid, consistent with commercial economy, and 
the latter gives highest efficiency of machine. In addition 
to these requisites, which are not peculiar to any style of 
engine, or to any one of the innumerable applications of 
steam power, the adaptation of the machine to driving the 
dynamo-electric apparatus of an electric lighting plant, 
compels the designing and constructing engineer to meet 
certain demands which, although not peculiar to this work, 
are, nevertheless, more imperative here than elsewhere. The 
principal of these requirements are effective regulation, 
compactness, simplicity of parts, strength and durability, 
and small cost, both of original purchase and of repairs. 
In the attempt to meet these demands, the modern " high 
speed engine " has gradually taken shape. 

In the time of Watt, a pressure of seven pounds of 
steam, with condensation, and a low piston speed, equal, 
usually, in feet per minute, to about one hundred and 
twenty-eight times the cube root of the length of stroke, 
according to Watt's own rule, represented standard practice. 
As time went on, steam pressures and piston speeds gradu- 
ally rose, and when, in 1849, Corliss brought out the typical 
modern "Drop Cut-off Engine" pressures of sixty pounds, 
and speeds of piston reaching 450 feet per minute were 
becoming usual. At such speeds, the "drop cut-oi7" was 
thoroughly effective, and the steam valve, detached from 
the driving mechanism, fell into its seat with sufficient 
promptness and accuracy, as to time of closing, to do good 
work; the governor had no other work to do than to detach 
the valve, and was thus able to regulate with an exactness 



ELECTRIC LIGHTING PLANTS 



that is still beyond competition. These engines are very 
extensively used to drive the smaller electric light machines, 
and particularly where a considerable number are to be 
driven together; they are not adapted to the work of driv- 
ing the large "dynamo," where it is desired to couple 
direct from crank-shaft to armature. 

As piston speeds increased, the drop cut-off became less 
satisfactory, where the load was variable. It became slowly 
undeistood, among builders and users of engines, that one 
important element of economy of fuel and cheapness in 
cost of engine is the maximum speed of engine consistent 
with endurance and safety. Speeds were, after a time, 
rapidly increased, the Porter-Allen engine leading in this 
movement, and small engines, working at high speed, dis- 
placed large engines of the older type. It soon became 
evident that this change must lead to the re-introduction 
of the " positive motion " classes of valve gear and expan- 
sion gear that Sickles, Corliss and Green had temporarily 
displaced, notwithstanding the fact that these builders had 
greatly increased the speeds of their engines. All the so- 
called " high-speed engines," which are best knowii in the 
market, are of this later type. The slower running engines 
are nearly all fitted with governors of the fly-ball class, 
geared, or belted, to revolve at a much higher speed than 
the engine itself ; but the great velocity of rotation of the 
new engines, from 200 to 500 revolutions per minute, in 
the small sizes, and often a piston speed of about 800 
times the cube root of stroke, permits the attachment of the 
governor directly to the shaft; and this is done in the later 
styles. This change of position of the governor, in turn, 



STEAM ENGINES FOR 



has led to a change in its construction. The balls, instead 
of being hung from a vertical revolving spindle by arms 
pivoted on that spindle, are attached to arms carried on the 
main shaft, or the driving pulley, and revolve in a vertical 
plane at right angles to the shaft; they are held in place 
against the action of centrifugal force by springs, and 
arranged to adjust the eccentric, and to vary the expansion, 
in a manner which will be plainly seen when studying their 
construction in the later sections of this paper, in 
which these engines will be described with the aid of care- 
fully made engravings. The high speed engine, as adapted 
to the work of directly driving the "dynamo," therefore, 
may be described as a high pressure, non-condensing 
engine, of short stroke, and high speed of rotation, with a 
positive-motion valve-gear, and regulated by a governor, 
which is usually mounted on the shaft, and so attached as 
to alter the expansion by varying the lead of the valve. 
Its essential features are high speed of rotation, good regu- 
lation by a positive gear, economy, simplicity, and compact- 
ness. It is this engine only, which is found to do good 
work under these peculiarly exacting conditions. 

It is proposed to study the best known engines of this 
and the earlier classes, and to compare them, with a view 
to bringing out their peculiarities and their special merits, 
while the purchaser will, besides, study the machine which he 
proposes to buy, to determine whether its material and work- 
manship are as excellent as are the principles of its design. 

The conditions demanded can here be merely outlined, in 
the following resume 1 of the requisites of successful practice: 

1. Report on Machinery and Manufactures. R. H. Thurston. Vol. iii. 
Reports of the Scientific Commissioners of the United States to Vienna; 1873. 



ELECTRIC LIGHTING PLANTS. 13 

1. A good design, by which is meant: 

a. Correct proportions, both in general dimensions 
and arrangements of parts, and proper forms and 
sizes of details to withstand safely the forces which 
may be expected to come upon them. 

b. A general plan which embodies the recognized 
practice of good engineering. 

c. Adaptation to the specific work to be performed, 
in size and in efficiency. It sometimes happens that 
good practice dictates the use of a comparatively 
un-economical design. 

2. Good construction, by which is meant: 

a. The use of good material. 

b. Accurate workmanship. 

c. Skillful fitting and a proper " assemblage " of 
parts. 

3. Proper connection with its work, that it may do that 
work under the conditions assumed in its design. 

4. Skillful management. 

In the endeavor to secure these requisites, it is generally 
advisable to use steam at a pressure not far from one hun- 
dred pounds per square inch. The benefits of increasing 
pressure diminish so rapidly above this point, that it is not 
yet certain whether it will, with existing engines, pay to 
carry pressure much higher. The ratio of expansion is to 
be determined with reference to this pressure, as well as to 
size of engine. It will usually be found even more wasteful 
to cut-off too short than to " follow " too far; and Rankine's 
principle of adjusting this point by consideration of the rel- 
ative cost of large and small engines, as well as the princi- 



14 STEAM ENGINES FOR 

pies controlling the economy of fuel, dictate, that for these 
engines, which are nearly always non-condensing and un- 
jacketed, the ratio of expansion must usually be low — say 
from three to five, as higher pressures range from sixty to 
one hundred pounds per square inch 2 — and that the termin- 
al pressure shall usually be kept some five or ten pounds 
above that of the atmosphere. 

Moderate " superheating " is found advantageous ; but 
it is seldom carried beyond about a hundred degrees above 
the normal temperature of the steam. " Steam jacketing," 
as practiced in nearly all compound engines, is of advant- 
age; but is not usually considered to pay for the added cost 
and risk in engines of the class here considered, and espe- 
cially in high-speed engines. The " compound " engine has 
not found a place in this field. Smeaton's idea — or rather 
Watt's, first attempted on a large scale by Smeaton — of sur- 
rounding the working fluid with non-conducting surfaces, 
is not yet found practicable with the high steam pressures 
and temperatures now usual. Its final adoption, however, 
is beyond doubt, as it is a far more promising system of 
economizing heat, now wasted, than either superheating or 
steam jacketing. The latter, indeed, is a method of intro- 
ducing a waste to check greater loss. 

Careful protection of external heated surfaces of the 
cylinder against losses by conduction or radiation, is always 
practiced where it can be conveniently done, and parts 
which cannot well be so covered are highly polished. A 
well polished surface transmits very little heat. 

Back pressure, a frequent cause of waste of power, is 

2. Ibid. Pp. 17, 18, 49. 



ELECTRIC LIGHTING PLANTS. 15 

reduced by making the exhaust parts large, and the exhaust 
opening of the valve rapid, and by giving "lead" to 
the exhaust, so that the steam shall leave the cylinder just 
before, rather than just after, the return stroke begins. 

Friction is reduced to a minimum by carefully propor- 
tioning the journals, and by securing free and continuous 
lubrication with a good oil or grease. 

An engine in which all the above requirements are fully 
met is certain to be a good machine. 

It is not proposed to compare the steam engine with the 
gas engine, or with other motors. The gas engine is, in 
many cases, likely to prove useful in consequence of its 
compactness, cheapness of first cost, freedom from risk, and 
small expense for attendance ; but it is expensive in use of 
fuel, and is rarely as little liable to annoying interruptions 
of operation as the steam engine, and also possesses other 
minor disadvantages. Nevertheless, Otto and Clerk, and 
other inventors and constructors, have greatly improved this 
machine of late, and have brought the expenditure, in ten- 
horse engines, down to twenty cubic feet of gas, or less, per 
hour and per horse-power ; and although this is still double 
the theoretical figure, no one can say how soon the latter 
consumption may not be much more closely approximated 
to. The gas engine is certain to find work in this direction. 
Hot air engines, as yet, give less promise ; but it would be 
rash to predict their total exclusion from the field. 

Water-wheels, especially when used exclusively for sup- 
plying power to the lighting plant, are, where available, 
thoroughly satisfactory prime movers. 

In studying the steam engine from the standpoint here 



16 STEAM ENGINES FOR 

taken, we will divide them, first, with reference to their 
method of driving the dynamo-electric machine, into two 
classes : 

i. Engines which may be used in driving by belt, and 
which are not adapted for direct connection. 

2. Engines especially designed and constructed to be 
coupled directly to the " dynamo." 

The first class of engines is in very extensive use, and 
is, by many of the more conservative engineers, still pre- 
ferred to the second. The latter constitute the so-called 
" modern " type of engine, and are gradually coming into 
use, some engineers adopting them, both for direct and for 
indirect connection. The best engineers are not yet fully 
in accord in regard to the question, whether they have 
passed the experimental stage. 



ELECTRIC LIGHTING PLANTS. 17 

III. 

Engines Indirectly Connected, only. 



THE CORLISS ENGINE. 

DIVIDING engines used in driving dynamo-electric 
machines into two principal classes— engines driving 
indirectly through gearing or belting, and engines directly 
connected to the armatures — we may profitably devote con- 
siderable space to the first class. And, although machines 
of the kind which have come to be distinguished by the 
appellation "high-speed engines " may be, and often are, 
indirectly connected, it is proposed to leave the examina- 
tion of such engines to a later article on directly connected 
engines, and here to describe only the " drop-cut-off " 
engines, or those with u detachable valve-gear/' which can 
only drive the armature of the " dynamo " indirectly. 

The first drop cut-off introduced, had a form patented by 
Fred. E. Sickles, in 1841. This engine was first built for 
mill purposes, by Thurston, Gardner & Co., at Providence, 
R. I., that firm then holding the Sickles' patents, except that 
the marine engine business was retained by Sickles. The 
modern stationary engine was thus introduced, and was 
soon extensively made known among steam users by its 
superior performance when competing with the older engines, 
which were then usually arranged to expand steam about 
one and a half times by the lap of the single three-ported 
valve. A few engines were built of a better design, fitted 
with an independent cut-off valve on the back of the main 



18 STEAM ENGINES FOR 

valve. These two last named engines would, at best, with 
good boilers use five or six pounds of coal per hour, and 
per horse-power, where the Sickles valve-gear would bring 
the consumption down to four. 

Regulation was always effected by a governor controlling 
a throttle valve. This governor was usually a common fly- 
ball governor, and its deficiency in power and lack of 
isochronism, the distance of the regulating valve from the 
engine valves, and the range of motion required in its 
operation, and the resistance offered by the packing of the 
steam, altogether, made this combination a very ineffective 
regulating apparatus. Thurston, Gardner & Co., sub- 
stituted for this the Pitcher hydraulic regulator and a 
register valve, which gave a much better regulation; this 
contrivance was also isochronous, /. e., it was capable of 
holding the engine at speed, whatever the variation of 
steam-pressure or of load. 

But an immense step in advance of this, then, best prac- 
tice was made by Geo. H. Corliss, a young Providence me- 
chanic, who had exchanged the role of sewing-machine inven- 
tor for that of the inventor of the most famous steam engine 
that has appeared since the time of Watt. The Corliss engine 
was patented in 1849, and rapidly came into use, its re- 
markable economy, when competing with the best existing 
engines, the peculiar business tactics of its builder, and the 
rapidly increasing demand for efficient, and especially well 
regulated, engines, combining to give it a wonderfully rapid 
introduction. 

The engine is an interesting illustration of a machine 
which is the representative of a peculiar type, each detail 



ELECTRIC LIGHTING PLANTS. 



of which is especially adapted to its place in that machine, 
and is characteristically different from the parts which per- 
form the same office in other engines. The leading features 
of this machine are: 

i. The use of four valves — two steam, and two exhaust 
— so placed as to reduce " clearance" to a minimum. 

2. The use of a rotating valve, capable of being cheaply 
and readily fitted up, of being easily moved, and of being 
conveniently worked by connections outside the steam 
spaces. 

3. The use of a " wrist-plate," caused to oscillate by a 
single eccentric, and directly so connected with all four 
valves that each may be given a rapid opening and closing 
movement, and be held open and nearly still, at either end of 
its range, by swinging the line of connection nearly into the 
line between centres, thus permitting nearly a full opening 
of port to be maintained during an appreciable interval, 
and a free and complete steam supply and exhaust. 

4. A beautifully simple and effective method of detach- 
ing the steam valve from the driving mechanism, and of 
insuring its rapid and certain closure at the proper moment, 
to produce any desired expansion of steam. 

5. A direct connection of the governor, so as to deter- 
mine the ratio of expansion, while so adjusting the power of 
the engine to the work to be done, that the variation of 
speed with changing loads becomes a minimum. 

6. Making this latter adjustment in such a way as to 
throw the least possible work on the regulating mechanism, 
and thus to give the governor the greatest possible sensitive- 
ness and accuracy of action. 



22 STEAM ENGINES FOR 

7. A form of frame and general design of engine, which 
gives maximum strength and stiffness, with least cost and 
weight. 

All these features are combined to form a steam engine 
essentially different, in general and in detail, from the 
engines contemporary with or succeeding it, except where 
the latter may properly be classed as Corliss engines. It 
rarely happens that an inventor succeeds in originating a 
plan so wholly and so essentially novel; and it is still less 
frequently the fact, that a peculiarly original device is 
found superior to all competing machines. In operation, 
the engine was found to exhibit a remarkable economy of 
fuel, and a singularly perfect regulation, and to be far more 
durable and more economical in cost of repairs, on the 
average, than rival builders supposed possible. It very 
soon took the leading place in the market. 

The inventor established himself at Providence, and put 
in operation a method of marketing his machine which 
was as novel and as successful as the mechanical device 
itself. He offered to put his engine in place of rival 
engines, either with a guarantee of a certain saving, and at 
a stipulated price, or, often, to take as his compensation 
the actual saving shown on the books in a stated time. 
This system was eminently satisfactory to the purchaser, 
both as making him safe against loss, and as giving him 
some of that confidence in the engine which the maker 
himself unquestionably possessed. Corliss' work fully 
justified his claims, and the expenditure of fuel was brought 
down to between three and four pounds per hour, and per 
horse-power, according to size and situation of the engine, 



ELECTRIC LIGHTING PLANTS. 23 

with occasionally much better figures in condensing engines. 

This engine is now built, not only by the Corliss 
Steam Engine Co., under the eye of the inventor, but by 
many other builders. It has found its way into every part 
of the world ; and the engineer visiting Europe will find & 
pleasure in observing the general adoption of this American 
invention in every country, and for every purpose. Euro- 
pean makers frequently modify the design, but rarely with 
the desired effect of securing an improvement in cost or 
efficiency, and very often with a decidedly contrary 
result. 

Corliss engines are now very frequently adopted in 
electric lighting, and are always belted to the dynamos. 
Their excellent regulation is as important a feature in this 
application, as is their economy in use of steam. When 
carelessly constructed, they are, of course, likely to prove 
wasteful and irregular in action. But that these engines 
can be made to give very perfect uniformity of rotation 
will be evident, when it is stated that the writer, in testing 
engines of this class, has found that the variation of speed 
was so slight as to be practically inappreciable, even when 
the amount of work thrown on or off, was a very large pro- 
portion of that done by the engine when working at its rated 
power. 

One other reason for the success of this engine is un- 
questionably the comparatively small cost of its construc- 
tion, where competing with the earlier forms of engine with 
detachable valve-gear. Its valve-faces, particularly, and 
their seats, are surfaces of revolution, and they, as well as a 
large part of the finished work about the engine, being 



24 STEAM ENGINES FOR 

almost wholly lathe-work, the cost of fitting up is com- 
paratively small. 

In detail, the engine consists, as shown in the illustration, 
page 19, of one of its standard forms, of a steam-cylinder 
sustained by any substantial connection with the foundation. 
The main pillar-block sustains the crank-shaft at the 
opposite end of the machine, and a strong brace, connecting 
these two pieces, forms, at the same time, a support for the 
crosshead guides. 

The four valves are placed at top and bottom of each 
end of the cylinder, their rotating stems projecting, and are 
moved by the "wrist-plate," set usually, as here, at the 
middle of the cylinder, the valve connections radiating to 
the four corners, where each is attached to the valve rock- 
ing-arm, the exhaust by pin-connections, the steam by a 
catch, which can be readily " tripped " by the adjustment 
of a little cam set on the valve-stem, behind the arm. 
When tripped, the steam valves are closed by a spring, or 
in engines now built by Mr. Corliss, by a " vacuum-pot," 
and by weights in his earlier engines, and in those of other 
builders. 

The governor is belted from a pulley on the main-shaft, 
and its oscillations are controlled by a " dash-pot," seen 
attached to the side of its standard. The governor, having 
no work to do but to set the tripping-cam, or the equivalent 
for it adopted by Corliss and others in various designs, is 
entirely free to adjust itself to the normal position due the 
speed of the engine, and thus is made perfectly capable of 
doing the best possible work. Many foreign builders have 
attached the Porter loaded governor to this engine. The 



ELECTRIC LIGHTING PLANTS. 25 

advantage is less obvious here than in engines in which 
more strength of action is needed. 

From what has been stated, it is seen that the Corliss 
engine came into use in consequence of its combination, to 
an extent up to that time unequalled, of several special 
features. Some of these points are not necessarily peculiar 
to the Corliss type of engine; but they, nevertheless, were 
peculiar to that engine at the time of its introduction. 
The main points were : the rapid and wide opening of the 
steam and exhaust openings; the shortness and directness 
of the ports; the resulting small clearance and "dead" 
spaces ; the quickness of closure of the steam valves ; 
the adaptation of the main valve to the functions of 
a cut-off valve ; the connection of the governor to the 
cut-off gear in such a manner as to determine the point of 
cut-off without being itself hampered by the connection ; 
the location of the exhaust ports at the under side of the 
cylinder so as to drain the cylinder thoroughly ; and the 
simple, easily constructed form of the machine and of its 
details. 

The general form of the engine has been preserved 
by nearly all copyists, and the parts of the valve gear 
and details of regulating mechanism have been seldom 
much modified. A few builders have, however, made 
changes which are worthy of notice, but which we have 
not time or space to study as they deserve. 

The action of the Corliss engine is as follows r 1 

The valves are driven by the eccentric rod through the 
" wrist-plate," E y vibrating on a pin projecting from the 

1. History of the growth of the Steam Engine. D. Appleton & Co., N. Y. 1S78. 



26 



STEAM ENGINES FOR 



cylinder. Links, E E>, E Z>, E F, E E, take motion, from 
properly set pins on this wrist-plate, to the steam valve 
rock-shafts, D, E>, and to the exhaust valves, E, E, moving 
them with a peculiar varying motion in such a manner as to 
open and close the ports rapidly, and to hold them open, when 
the valves are off the ports, in such a way as to give the 
least possible loss of pressure during the exit or the entrance 
of steam. The links leading to the steam valves are fitted 




The Corliss Engine. 



with catches, or latches, which may be disengaged, as the 
valve opens, at any desired point within about half stroke; 
and the time of this disengagement is determined by the 
rotation of a cam seen on the valve stem above D, which 
cam is rotated by the governor through the rod If, leading 
off to the left. The slowing of the engine, in consequence 
of reduced steam pressure or of increased load, causes the 
catch to hold its contact longer and the steam to follow 



ELECTRIC LIGHTING PLANTS. 



2? 



farther, and the reverse. When the catch is disengaged, 
the valve is closed by a spring or weight attached to the 



rum 




w 
p 

-I 

u 

g 

w 



o 

CJ 

w 
w 

H 



vertical rods seen connected to the rock-shaft arm. Corliss 
uses a device in place of this which is not here shown. The 



28 



STEAM ENGINES FOR 



dash-pots are under the floor, in the case here illustrated, 
or on the column supporting the governor in the engines 
just referred to. It is always an air dash-pot. The device 
invented by Sickles was a water dash-pot. 







The standard form of Corliss valve is very well exhibited 
by the illustrations here given, which are taken from the 
drawings of Mr. Harris. 



ELECTRIC LIGHTING PLANTS. 29 

V 



Those marked A are the steam, and those marked B are 
the exhaust valves. Both consist, as is seen, of cylinders, 
parts of which have been cut away, leaving the working and 
bearing surfaces of no greater extent than is necessary to 
subserve the purposes of the valve. These surfaces are of 
the simplest possible form and are easily fitted up in the 
lathe. In order that they may come to a bearing with cer- 
tainty, and without regard to the position of the spindle 
relatively to the valve, they are made with a longitudinal 
slit into which fits, without jamming, the blade of the rock- 
shaft. The valves are thus allowed to come to a bearing, 
and even to wear down in their seats without causing leakage. 
The next Fig. shows the arrangement of this valve as 
seen in longitudinal section of the chest. As this maker 



Harris-Corliss Valve. 

constructs it, the stem goes through a fitted opening, with- 
out stuffing box, and the slight drip is carried off from 
the closed space at D ; thus none escapes into the 
engine room. The steel collar at F, which is shrunk on 
the stem, fits into the recess at a and serves as a packing. 
As the tendency of the stem to shift outward always causes 



30 



STEAM ENGINES FOR 



the collar to wear to a fit, it is not likely often to wear leaky. 
Another detail of interest in the Corliss engine is the 



H 

K 
H 

d 

> 



O 





"dash-pot." When the valve is suddenly closed, some 
device is necessary to prevent jar at the instant of its com- 



ELECTRIC LIGHTING PLANTS. 31 

ing to rest. This device is the dash-pot. The form adopted 
by Corliss consists of a shallow cup into which a piston on 
the valve stem fits, cushioning the enclosed air, and thus 
checking the motion of the valve without shock. This dash- 
pot, made by Watts, Campbell & Co., who have successfully 
introduced Corliss engines into electric light establishments 
in New York city and elsewhere, is that seen in the Figs. 

The annular piston, E, E, fits the cylinder, Z>, Z>, E } E } 
and a space, seen above B, forms a vacuum chamber which 
assists the spring or weight, closing the valve by the form- 
ation of a more or less complete vacuum, as the pis- 
ton is raised while the valve is opening. A small cock, 
not seen, is arranged to adjust the degree of ex- 
haustion of this chamber. When the valve has nearly 
reached its seat, the piston Z>, passes the opening from F 
into the outer space and the enclosed air then acts as a 
cushion, checking the movement of the valve. In the 
engines of these builders, great care is taken to keep the 
cold exhaust steam clear from the cylinder as it passes out, 
in order to prevent the condensation which occurs where 
this precaution is neglected. 

Many Corliss engines are already at work driving elec- 
tric lighting apparatus, and are giving good satisfaction, 
according to the testimony given the writer by the officers 
of the companies using them. One, built by the Corliss 
Steam Engine Co., is at work at Providence, R. I., driving 
nine dynamos, and a number are in use in New York city, 
and other large cities of the United States and of Europe. 

At how high a speed they can be operated with satisfac- 
tion to the user is not definitely known. The writer has 



32 STEAM ENGINES FOR 

known one of these engines, coupled to a fast running roll- 
train, to be driven without apparent difficulty for several 
years at a speed of 120 revolutions per minute, although or 
four feet stroke. This engine is still running. Those who 
use, as well as the engineers who build, this class of engines, 
however, are apt to be conservative and to prefer the mod- 
erate speeds with indefinite endurance, to higher speeds with 
a shorter life of engine and greater cost in keeping in 
repair; *and to consider that the satisfaction of having a 
prime motor, which is not likely during their business lives 
to give them any trouble, is more than a compensation for 
any possible saving in dollars and cents to be effected 
by the adoption of the higher velocities of piston and of 
crank-shaft rotation. 



THE WHEELOCK ENGINE 

is an ingeniously arranged engine of the class considered 
in this division of the subject. 

Its form is seen in the accompanying engravings. 

The steam chest is placed below the cylinder and the 
steam and exhaust valves are set side by side, the latter 
serving both as induction and eduction valve, and having 
'the same action, nearly, as the common three ported slide 
valve, while the function of the former is principally that of 
a cut-off valve. The latter, or main valve, is set nearest the 
end of the cylinder and the exhaust steam is thus permitted 
to escape directly and promptly from the engine. The 
valves are coned, slightly, and may be adjusted to take up 
wear, or to relieve pressure on their seats. These valves 



ELECTRIC LIGHTING PLANTS. 35 

are carried on steel trunnions, and with hardened surfaces 
of contact are but little subject to wear. The steam or 
cut-off valve is set further away from the cylinder than in 
the standard arrangements of Corliss and other builders of 
that class of engines, and this enables the maker of this engine 
to secure a single port with reduced clearance and less 
liability to leakage, should the expansion valve leak. In 
this engine — and it should be the case in every engine in 
which the regulator is driven by belt — the connection from 
shaft to governor is so made that the breaking of the belt 
permits an automatic closing of the valve and the stopping 



The Wheelock Valves. 

of the engine. The regularity of motion of the class of 
engines described in this section, may be inferred from the 
fact stated in regard to the engine here studied, that it has 
been known to vary but a half revolution per minute when 
five-sixths of the load was thrown off. 

Engines of the class described in this section have dis- 
played an economy in the use of fuel that has been rarely 
equalled by the best type of compound engine, working 
under the same conditions of steam supply. With good 



36 STEAM ENGINES FOR 

boilers, they have given the horse-power with a consumption 
of two pounds an hour for condensing engines, and three 
pounds for non -condensing engines. They have quite 
often demanded but a ton of coal for 100 barrels of flour 
ground, in well arranged mills; and one and a quarter tons is 
a very usual figure. A number of good makers are now 
building such engines, and the purchaser can readily suit 
himself if desirous of selecting an engine of any grade, either 
as to cost or excellence of construction. They are well 
adapted to driving either large or small electric lighting 
plants; and, if purchased of a reliable maker, may be con- 
fidently expected to give satisfaction. 



THE GREENE ENGINE. 

AT EARLY all "drop cut-off engines " are constructed, 
•^ ^ like those described in the preceding article, 
with a single eccentric, which drives both the steam 
and the exhaust valves. Both sets of valves must, therefore, 
have the same motion relatively to the piston, except so far 
as their motion can be modified, as in the Corliss engine, by 
the method of connection of valve and eccentric. They 
must stop and start at the same instant, and their motion 
during their travel must be more or less similar. But such 
a system is controlled in its action by the necessary motion 
of the exhaust valve. That valve must be adjusted to 
open and to close very nearly at the beginning and 
the end of the return stroke, in order that the exhaust 
may be prompt and free, and that the compression shall 
be right. The movement of the gear, on the steam side, 



ELECTRIC LIGHTING PLANTS. 39 

must thus be also one which shall open the valve 
to take steam at the commencement of the steam stroke, 
and, if the valve is not tripped, close the port at the end 
of that stroke. It is further evident, that if the valve is to 
be detached by its own motion, it can only be tripped dur- 
ing the forward part of its movement, and that, passing that 
stage, and commencing to return before the cut-off takes 
place, the valve must be allowed to remain undetached 
until the end of stroke, and steam must follow full stroke. 
An engine thus constructed, and so adjusted to its work as 
to cut-off at about half stroke, will evidently, if the work or 
the steam pressure becomes variable, be likely to operate 
very irregularly, at one time cutting off at a little inside 
half stroke, and then jumping to full stroke. This varia- 
tion of steam distribution may thus itself introduce a dis- 
turbing element, and the engine may give a very unsatisfac- 
tory performance. Such an adjustment of power of engine 
to the work to be done, does not often take place in engines 
of the class which is here studied, as the best point of cut- 
off is usually not far from one-third or one-fourth stroke, 
and the variation in the load is not often great enough to 
cause serious difficulty in the manner described above. 

One advantage possessed by the arrangement of valve 
gear, thus subject to criticism, is that, should, as sometimes 
happens, the valve fail to close, or should it lag behind 
very greatly, in fast running engines, it is certain that it 
cannot be left open beyond the end of that stroke, as the 
returning motion of the valve-gear will bring the latch into 
gear again, and will insure its closing. Mr. Corliss con- 
siders this point of sufficient importance to make it inex- 



40 STEAM ENGPNES FOR 

pedient to drive the steam valves by the method to be 
described in this article. It is undoubtedly an advantage 
to be able to secure such an arrangement of valve-gear 
that the ratio of expansion may be varied by the governor 
from the beginning to the very end of the stroke, so that 
the engine may adapt its steam supply to any load that 
may be thrown upon it, whatever the extent of that varia- 
tion may be, and to cut-off at any point from end to end 
of the stroke. This can be done by the adoption of a gear 
of the class known, for many years past, from the time of 
the earliest steam engines in fact, as the " plug-tree " form of 
valve-gear. It was this class of gear that was used on engines 
before the days of Watt, that greatest of inventors, for pump- 
ing out the deep mines of Great Britain — the Newcomen 
engine. It may be still seen in use on all so-called Cornish 
engines, which are to be found in the water works of this and 
other countries — the most costly, cumbersome, and unsatis- 
factory style of engine which has been applied to that kind of 
work in modern times. The distinguishing feature of this 
gear, is, that it is so adjusted, that the motion of the valve is 
produced by a mechanism which begins and ends its move- 
ment with the action of the piston; in the Cornish engine 
it is actuated by the engine beam. It is easy to obtain a 
motion of this character, by the use of an eccentric, by 
simply setting it so as to make its throw directly with, or 
opposite to, the crank. In such a case, it is seen that the 
exhaust valve must be driven by an independent eccentric, 
and the cost of the engine is thus somewhat increased. 
This is not a large item, however. The " Greene engine * 
is an engine fitted with such a valve-motion. 



ELECTRIC LIGHTING PLANTS, 



41 



In the accompanying illustration, 1 which exhibits this 
machine, the valves are seen to be four in number, as in the 
engines already described. They are flat valves, instead of 
cylindrical, and are thought by the inventor to be better 
than the latter, as being easier to refit when worn, and as 
being less liable to become leaky. The cut-off mechanism 
consists of a sliding bar, A, driven by an eccentric, set to 




Greene Valve Motion. 



give it motion parallel to the centre line of the cylinder, and 
with a movement co-incident, as to time, with the motion 
of the piston; of a pair of " tappets," C, C, set in this bar 

1. Hist, of the Growth of the S'eam Engine D. Appleton & Co., N. Y., 1878. 



42 STEAM ENGINES FOR 

and adjustable vertically in such a manner as to engage the 
rock-shaft arms, B, B> on the ends of the rock-shafts, -is, F % 
which rock-shafts are attached to the valve-links inside the 
steam chest; of a set of springs which hold these tappets 
up to their work, and in contact with the " gauge-bar " 
behind the bar, A, and out of sight in the drawing. This 
gauge-bar is adjusted to the proper height, and is varied in 
position, as the load varies, by the action of the governor 
which is connected to the gauge-bar by the rod extending 
up to it at G The exhaust valves are seen below, and are 
driven by the second eccentric there shown. They are so 
placed as to thoroughly drain the cylinder of all water 
carried into it by priming, or produced by cylinder con- 
densation. The eccentric driving these valves is set 
at right angles to the position of the crank. In con- 
sequence of this independence of the two sets of valves, 
this engine can cut-off at any point in the stroke during a 
complete half revolution of the crank. This form of engine 
was invented by a Providence mechanic, Mr. Noble T. 
Greene, and was patented in the year 1855. Mr. Greene, 
then of the firm of Thurston, Greene & Co., introduced this 
engine a few years after the merits of the drop cut-off had 
been proven by Sickles and Corliss so fully that it was easy 
to secure a market for new devices of this class; and the 
introduction of this engine has had much to do with the 
rapid progress of these more economical kinds of engine. 

The form of the engine has been somewhat modified at 
various times, although its characteristic features have been 
carefully preserved. The steam valve, as designed by the 
writer, who, at the time of its first appearance, had an 



ELECTRIC LIGHTING PLANTS. 



43 




Thurston's Valve. 



occasional opportunity to exercise his powers as a designer 
on this engine, is seen in the next Fig. 1 

The valve, G, If, cover- 



ing the steam port, Z>, in the 
cylinder, A, B y is driven by 
the rod, J> J y which is con- 
nected to the rock-shaft, M, 
by the arm, Z, K y in such a 
manner that the line, K, I, 
will, when prolonged, inter- 
sect the valve-face at its middle point G; it is thus so set 
that the line of action of the link, K, f 9 meeting the valve 
seat directly under the middle of the valve, does not 
produce any tendency to rock the latter, and thus to cause 
wear at the edges, or leaks of steam past the valve into the 
port. 

The latest form of the Greene engine, familiar to the 
writer, is that now constructed by the Providence Steam 
Engine Co., and shown in the large illustration, page 35. In 
this engine, the steam valves are connected to the cut-off 
mechanism, by a set of rods or stems running parallel to 
their seats, and emerging into the air through stuffing 
boxes, properly provided with easily set and easy working 
packing; these valve stems are connected to the rock-shafts, 
and are driven as in the arrangement already described, 
very nearly; this design has some advantages over the old, 
in keeping the working parts, and especially the joints, out 
of the steam space. The exhaust valves are gridiron slides, 
set to travel across the line of the cylinder, and driven from 



1. Sup lied by D. Api leton & Co. 



44 



STEAM ENGINES FOR 



a horizontal rock-shaft, extending forward to the eccentric 
on the crank-shaft; the governor is a Porter loaded 
governor, driven by a belt from the main shaft; the cut-off 
mechanism is illustrated in the last of this series of illustra- 
tions. 




Greene Trip Motion. 



The tappets, A, A, r.re carried by the rock-shafts, J % 
y, which, in turn, drive the arms, F y F, and the valves 
attached to the stems, G, G, passing through the stuffing 
boxes, H f H; the tappets, B, B, engage these rock-levers, 
and are adjusted vertically by the governor rod, E>, and 
held up against the gai>ge bar or the rock-lever, as the case 
may be, by the springs set in the sliding bar. When the 
speed of the engine is above that for which the engine is 
set, the governor, acting through the rod, £>, depresses the 
tappets, and they do not retain their connection with the 
rock-lever as long as when at normal speed; when the speed 



ELECTRIC LIGHTING PLANTS. 45 

falls below that fixed by the constructor, the governor rod 
rises, and the tappets are thus permitted to rise, and to 
remain in contact with the rock-lever, holding open the 
steam valve for a longer period than before. The longer the 
valve is to be kept open, and the farther the steam is to 
follow, therefore, the wider does the port open to steam. 
When the tappets travel to the point of cut-off, they swing 
clear of the rock-levers; the weights, acting together with 
the pressure of steam upon the valve-stem area, quickly 
shut the port, and the steam is allowed to expand from that 
point on to the end of stroke; the higher the tappets are 
permitted to rise, by the elevation of the gauge-plate, the 
greater the ratio of expansion; the further they are 
depressed, the shorter the cut-off. As these engines are 
constructed, they are capable of cutting off steam anywhere 
between the beginning and three-quarters stroke; the latter 
limit is determined by the lead, and by the margin thought 
necessary to secure certainty of closure of the valve, when 
tripped, before the piston reaches the end of its stroke. 
To follow farther would not be likely to be of advantage, as 
the gain in the mean total pressure would be compensated 
by the loss due to a retarded exhaust. A safety stop- 
motion is combined with the governor connection, in such 
a manner, that if the belt breaks, or is thrown off its pulleys, 
the steam will be at once shut off, and the danger of acci- 
dents, such as sometimes occur with a run-away-engine, is 
avoided. The valves and seats on the exhaust side are 
both easily removable, from the outside, have outside con- 
nections, and are readily adjusted without interference 
with the steam side. 



4 6 STEAM ENGINES FOR 

These engines have been, next to those of Corliss, the 
pioneers in the movement, during the past generation, 
toward economical working of steam. An engine built 
upon this plan, substantially, by the firm of Thurston, 
Gardner & Co., nearly a quarter of a century ago, from 
designs prepared by Mr. E. D. Leavitt, Jr., for a well- 
known Eastern mill, had steam-jacketted cylinders, 26% 
inches in diameter, 5 feet stroke of piston, made 50 revo- 
lutions per minute, with steam at 100 pounds pressure in 
the steam chest, and, on trial, worked down to a consump- 
tion of 1.98 pounds of coal per horse-power and per 
hour; the guarantee was 2 pounds. Its fly-wheel, designed 
by the writer, who was then just out of college, weighed 
about 20 tons, was fitted up as a mortice gear, with cut 
hickory teeth, and was given extremely small side clear- 
ance; the motion of the engine was so smooth, however, 
that the presence of the gear was hardly noticeable. This 
engine was fitted with the gridiron slides, as in the above 
illustration; they were driven by sliding cams, thus ob- 
taining a rapid opening and closing of the exhaust, and a 
slow movement while in the intermediate position, with the 
port either open or closed. This was a remarkably good 
piece of work for that time, and has not often been 
excelled since. 

This engine, like other engines with drop cut-off valve- 
motion, is not adapted to such high velocity of rotation as 
to permit it to work safely at the speed of even the largest 
and slowest of the modern "dynamos; " but, belted to the 
machine, it will give as great economy, and as great per- 
fection of regulation, as engines of the preceding class. It 



ELECTRIC LIGHTING PLANTS. 47 

is evidently so arranged that no load is thrown upon the 
governor, and the effort to detach the steam valve is, there- 
fore, not liable to cause any oscillation in the cut-off gear, 
or variation in the speed of the engine. In all these en- 
gines, the difficulty met with by the designer is, not to 
secure this independence of the governor from the action 
of the valve-gear, but to prevent the irregularity which 
comes of the oscillations of the governor itself. The dash- 
pot attached to the governor, or, sometimes, a friction 
mechanism, prevents such irregularity. 

This valve-gear does not as conveniently adapt itself to 
the vertical engine as some others, but one of the first 
engine-cylinders ever designed by the writer, was built with 
this gear, and was set vertically. It gave perfect satisfac* 
tion, if the fact that it was never reported to the shop for 
repairs, so far as the writer has yet heard, may be taken as 
evidence of its successful operation. 1 

This engine was introduced over a quarter of a century 
ago, in the face of a strong competition from the Corliss 
engine — a fact which is, perhaps, the best evidence that it 
had merit — and by the same methods which Mr. Corliss 
had proved so effective. Guarantees were given of per- 
formance, and forfeitures were provided for in the contract; 
or else the agreement was accepted to take as payment the 
saving actually effected in a fixed period of time — usually 
from two to five years, according to the character of the 
machine displaced. One of these engines, with which the 
writer was familiarly acquainted through his indicator, and 

1. This engine is Ptill in use, after 22 3 ears service, and drives a set of 
dynamos at South Webster Mass. 



48 STEAM ENGINES FOR 

which displaced the rival engine on such a guarantee, has 
now been in operation 23 years, and is reported to be to- 
day still in perfect order. The engine referred to above as 
having given so excellent a performance, was put in under 
an agreement by which the builders agreed to forfeit $1,000 
per ]^ pound that the coal consumption should fall short 
of the guarantee. The manufacture was interrupted for 
some years by an injunction secured by Mr. Corliss, after 
a suit brought by him for infringement, but was recom- 
menced after the expiration of the Corliss patent, and has 
proved a successful enterprise, notwithstanding the fact 
that its constructors have depended, apparently, upon the 
performance of the engine itself for advertisement — a con- 
servative system of doing business which few manufacturers 
adopt, at present. 

All three of the great inventors and introducers of the 
modern American type of steam engine — Sickles, who 
brought into use the drop cut-off; Corliss, who gave the 
stationary engine, its now standard form, as well as devised 
his peculiar valve gear; Greene, who applied the principles 
of this system of working steam to the plug-tree form of 
valve gear, — are now still living. Mr. Corliss has acquired 
wealth, as well as fame; his predecessor and his rival, how- 
ever, have attained less fame — much less than they are en- 
titled to, and still enjoy all the advantages which poets 
ascribe to the possession of small means. Neither of them 
expects to be able to build a monument, in the shape of a 
great technical school, such as it is becoming customary for 
wealthy engineers, like Stevens, and Rose, and Stone, to 
erect. 



ELECTRIC LIGHTING PLANTS. 



51 



There are other engines belonging to the class here 
considered — the engines having a detachable cut-off valve 
closed independently of the motion of the valve-gear, — of 
which the space proposed for these articles will not permit 
descripton. Among these are the Wright engine, con- 
structed by one of the oldest and best known designers in 
the country; the Brown engine, a machine which has been 
extensively adopted for driving mills in New England, and 
is famous for the excellence of its workmanship and finish, 
as well as for its durability and efficiency; the Fitchburg 
engine, and others. 



52 STEAM ENGINES FOR 

IV. 
Engines Capable of Direct Connection. 



THE PORTER-ALLEN ENGINE. 

^T^HE essentials, in the construction of the steam engine 
-"- with a view to the economical production of power, 
as has been seen in the introductory part of this series of 
articles, include special provision against loss of heat and 
condensation of steam, at entrance into the steam cylinder, 
by the action of the metal surfaces to which it is exposed 
on all sides at the beginning of the stroke. One of the 
methods of securing this economy in the working of steam, 
has been stated to be the driving of the engine up to the 
highest safe velocity of piston, and giving it a maximum 
speed of rotation. The time allowed for condensation of 
each charge, and for the necessary change of temperature 
preceding such condensation, is thus reduced, and the 
amount of steam condensed being thus made a minimum, 
in any given time, the percentage of loss of the increased 
quantity of steam worked off by the engine becomes the 
least possible. The engine does a greater amount of work, 
and is subject to less loss. Thus the work to be done being 
fixed, it is done by a smaller, and, other things being equal, 
a less costly engine, and at the same by a more economical 
machine. 

Although this seems a sufficiently simple and axiomatic 
philosophy, and although the general tendency of practice 
in steam engineering had been plainly in this direction for 




Pair of Porter-Allen Engines. 



ELECTRIC LIGHTING PLANTS. C5 

many years, these points had not, up to a comparatively 
recent time,been recognized by constructing engineers, and 
fheir progress had been slow and difficult. The older firms 
who were engaged in the building of what were then called 
"expansion engines," were the first to detect this movement 
and its cause, and they led off, in a very conservative way, 
toward the construction of faster engines. The firms 
already mentioned as leading in the movement toward cor- 
rect practice, came up to speeds far ahead of those common 
among other makers, and secured an advantage that was 
sufficient to prove unmistakably that they were in the right 
track. They did not, however, modify their designs in any 
great degree, with a view to adapting them to very high 
speeds. Their valve-gears were not of a kind well 
fitted to high speed of rotation; the builders, were them- 
selves disinclined to accept the risks undeniably attendant 
upon rapid change in this direction, and the public to whom 
they looked for a market were not educated up to such a 
point as would make it safe to attempt to go on very 
rapidly. A rather slow engine, with its comparative 
immunity from risk of serious accident in case any little 
derangement should occur, and with its greater durability 
under the ordinary conditions of use, was, by the great 
majority of designers, builders, and steam users, thought a 
far better investment than a fast engine, however well 
adapted to the radical illustration of a very interesting, but 
apparently impracticable, philosophy. 

The first man to take up this matter with a will, and 
with a faith and a determination that were equal to the 
task, was Mr. Charles T. Porter, a young lawyer turned 



56 STEAM ENGINES FOR 

engineer, and Mr. John F. Allen, when the writer first knew 
him, a skillful mechanic, who was showing the natural bent 
of a real inventor, in the production of new devices, while 
engaged in the management of some of the best engines of 
20 years ago. The valve-gear of the Porter-Allen engine, 
is the invention of Mr. Allen, and its governor and general 
arrangement are due to Mr. Porter. It was Mr. Porter, 
also, who, by his courage, persistence, skill in business, and 
general good sense and management, finally, after years 
of struggle to secure good construction and workmanship, 
brought the engine into use in spite of every discourage- 
ment, whether due to circumstances, to direct opposition of 
competitors, or to public sentiment in favor of conservatism. 
There are some interesting problems which present them- 
selves to the engineer who attempts to design an engine to 
be operated at very high speed — problems which are by no 
means easy of solution, except to the boldest of innovators. 
One of these points of difficulty has already been considered. 
When the speed of revolution is increased, it is evident that 
a limit must sooner or later be attained at which the drop 
cut-off must be exchanged for some " positive motion " 
gear. But the various forms of such gearing familiar to 
engineers when Messrs. Porter and Allen became acquainted 
with each other, years ago, the still common three-ported 
valve, such as is used on locomotives, the Meyer valve with 
its cut-off valve on the back of the main valve, and kindred 
devices, were not adapted to the conditions sought by the 
engineer looking for a good system of expansion. They 
were simple and inexpensive, and could be used at any 
practicable speed of engine; but they did not always give a 



ELECTRIC LIGHTING PLANTS. 57 

satisfactory distribution of steam. They usually produced a 
retarded steam supply, a " throttling " of the steam at the 
point of cut-off, which was not at all such as would satisfy 
the engineer familiar with the prompt action, and the 
" sharp corners " of the indicator diagram from the class 
of engine then taking the market. The dependence of the 
several parts of the motion upon each other was another 
objection to these devices, and the load which they threw 
upon the governor was a fatal defect, as the governor was 
then arranged and connected. Mr. Allen's invention placed 
in the hands of Mr. Porter just the device that he needed 
to carry out his idea of a fast engine. 

This arrangement consists of a single eccentric driving a 
link motion to operate the steam valve and to work the 
exhaust at the same time. The link is controlled by a 
Porter governor, and is so connected and driven that the 
gear may be readily and quickly adjusted by the governor 
to any desired point of cut-off. 

The eccentric and link are shown in the next illustra- 
tion. The eccentric is set on the shaft in such a position, 
that its motion is co-incident with that of the crank. The 
link is a slotted curved arm, forming one piece with the 
eccentric strap, pivoted at the middle on trunnions sustained 
by an arm rocking about a pin set in the bed of the engine. 
The upper end of the link carries a pin, from which a rod 
leads off to the exhaust, which is driven without variable 
connections. The link-block is fitted to work in the slot 
of the link, from the end nearest the exhaust rod pin, down 
to the point opposite the pivotal point at which the trunnions 
are set. When it is at the upper end, the throw of the valve 



58 STEAM ENGINES FOR 

is a maximum; when at the lower point, it is a minimum. 
As the link-block is moved up and down in the slot, the 
motion of the valve is varied, and the ratio of expansion 
correspondingly altered. By an ingenious adjustment of a 
still more ingenious form of valve-motion, it is thus possible 



The Allen Link. 

to obtain a valve movement of perfect precision at all 
speeds, and on both the forward and the backward stroke, 
with a quicker closing action, as the cut-off is later. The 
steam is. allowed to enter the cylinder, at nearly boiler 
pressure, almost up to the point of cut-off, and the expan- 
sion line is a smooth curve very nearly from the junction 
with the steam line. 



ELECTRIC LIGHTING PLANTS. 59 

This form of indicator diagram has been usually con- 
sidered peculiar to the class of engine described in the pre- 
ceding articles. In this case, the diagram is nearly as sharp 
in the corners as those from a drop cut-off engine. The 
range of expansion is from the beginning of the stroke to 
about five-eighths. 

There are four valves, as shown in the next Fig., which 
is a section through the steam cylinder showing valve, ports, 
and general construction. The two valves at the upper side 
of the cylinder are the steam valves; the lower are the 
exhaust valves. This section is, however, horizontal, the 
valves being set on their edges at either side of the cylinder. 
The exhaust valves are so placed as to drain the cylinder of 
any water that may have entered with the steam, or may 
have been produced by internal condensation. Both sets of 
valves are so made, and set, as to be well balanced, and 
so as to be capable of having the wear taken up when it 
occurs. The steam valves are provided with packing 
plates, which are adjustable by hand, to make them steam 
tight, as well as to secure a perfect balance. Each valve 
is placed in a separate valve-chest, and can be independently 
adjusted. Each valve opens four ports; each is so set, that 
it is actuated by a rod in the line of its own centre; and all 
are thus rendered but little liable to either wear or leakage. 

The rock-shaft arm on the intermediate rock-shaft, 
seen in the large Fig. between the eccentric and the 
steam valve stem, assists in securing the quick opening and 
closing motion essential to a satisfactory distribution of 
the steam. 

The features which have now been described, are not 



60 STEAM ENGINES FOR 

necessarily distinctive of a " high speed engine. ,, A posi- 
tive motion valve-gear, and a good steam distribution, are 
desirable in such engines, and the first point is, in fast run- 
ning machines, an essential requisite; but the Allen engine, 
so far as it has been described, may be as well considered 
a slow as a fast engine. There are some details, to which 
r ve are now to turn our attention, which are essentially and 
peculiarly characteristic of the class to which this machine 
is assigned. Among these points are the strength and rig- 
idity of parts which distinguish such engines; the great 
nicety of fitting; the excellence of all material in every 
part exposed to the straining action of inertia, and the 
minor but yet important modifications of details to adapt 
them to service in a machine, in which the slightest play in 
joints or bearings will be certain to make trouble. The 
bed is of peculiar design and is enormously stiff and solid, 
especially in those parts which take the stresses of the re- 
ciprocating pieces. It is broad and deep, with the line of 
thrust of piston rod carried close to its surface between the 
guides, and with a box form which gives great resistance to 
forces tending to twist it. 

The steam cylinder is secured to the bed by the end, a 
construction adopted by Corliss many years ago, and one 
which gives all desirable strength, with freedom from those 
strains which come of connection of two large masses at 
different and constantly varying temperatures. The whole 
of its exposed surface is covered with lagging to prevent 
loss of heat by radiation. The main journal boxes are 
made in four pieces, and are set up by adjustable wedges, 
so set as to avoid the springing of the shaft that is some- 



ELECTRIC LIGHTING PLANTS. 63 

times found to occur with a less effective arrangement. 
The main-shaft journals, and the journals of the crank-pins, 
are made with especial care, skillfully ground to size and 
form, and nicely finished before the engine is assembled. 
The pin is always of " mild " steel, carefully case-hardened 
to give it a surface that will wear well and will not " cut." 

The provisions for lubrication in such engines are not 
the least important of its details. The engine presents 
some neat devices in this respect which we have not space 
to describe. 

One of the most remarkable and interesting of the fea- 
tures, which especially adapt this engine to great speed of 
rotation, and one, the developement of which, in its theory, 
as well as in practice, is due to Mr. Porter, is a peculiar 
adjustment of weight of moving parts to the equalization of 
stresses on the line of journals between the piston and the 
crank-shaft. When the steam is allowed to follow the pis- 
ton only to some point early in the stroke, the ratio of 
expansion being made, as is usual, between three and five, 
the rapid fall of pressure, during expansion and up to the 
end of the stroke, causes a very great variation in the effort 
exerted upon the crank-pin and other journals. As the 
maximum pressure occurs when the crank is passing the 
centres, and while the work done usefully is, in consequence 
of the slight travel of the piston, very little, and as, at the 
same time, the considerable movement of the pin under this 
pressure causes a considerable loss of work by friction, and 
as it is advisable to secure a uniform effort producing rotation, 
it is evident that it is desirable to find a method, if possible, of 
equalizing the pressure throughout the stroke without sacri- 



6 4 STEAM ENGINES FOR 

ficing the advantages of expanding the steam. The action 
of inertia in the moving parts is made by Mr. Porter the 
means of securing this result. 

At the beginning of the stroke, the inertia of the piston, 
its rod, the crosshead, and to a certain extent the connect- 
ing rod, all reciprocating parts, causes them to offer a cer- 
tain resistance to the accelerated motion which they are 
compelled to take up. This resistance becomes less and 
less up to zero at half stroke, the point at which their velo- 
city is a maximum. Passing this point, they are rapidly 
retarded, and this same property of inertia causes them to 
offer a resistance to retardation, which resistance now is felt 
as an impelling force at the crank-pin. Thus, the effect of 
the presence of these heavy masses in the line of connec- 
tion, produces a reduction of pressure upon the pin at the 
commencement, and an increase of pressure at the end of 
stroke. But, in consequence of the varying action of the 
steam producing an excess of pressure at the beginning, 
and a deficiency of pressure at the end of stroke, we may 
combine these two effects, and the result is a comparatively 
uniform load upon the crank-pin throughout the stroke. 

This compensation is capable of being, in many cases, 
very nicely adjusted by properly proportioning the weight 
of the reciprocating parts. As engines are usually propor- 
tioned with a view to strength of parts simply, the piston, 
crossheads, and rods are too light to be of much service in 
this way. Mr. Porter adopted the plan of making his pis- 
ton and crosshead of such weight that the equalization of 
pressures should be the most complete possible, and this 
involved making them decidedly heavier than they are made 



ELECTRIC LIGHTING PLANTS. 6 c 

in common practice, even when his engines were driven up 
to a 'opeed which had never been before attempted in sta- 
tionary engine practice. It is evident, however, that at some 
higher speed, the weights of these parts, as proportioned 
for strength simply, would be sufficient to give this desir- 
able adjustment of the load on the crank-pin. There Is no 
reason to suppose that this, which would seem to be a 
natural speed of the steam engine, may not be at some 
future time attained. 

An interesting fact in this connection, is that Mr. Porter, 
although not professionally a mathematician, or educated 
as an engineer, first worked out the relations of these forces 
by a simple process, and applied his results to his practice, 
and that, subsequently, at his request, a distinguished ma- 
thematician, Dr. Barnard, President of Columbia College, 
attacked the problem by the methods of the higher analysis, 
and revealed the laws involved, and verified completely the 
work of the engineer. 

The large engraving on page 49, represents one of three 
pairs of engines in use at the Willimantic Linen Company's 
mill. They are nj4 inches in diameter of cylinder, and 16 
inches stroke of piston; they make 350 revolutions per 
minute. This is not considered a high speed for these 
engines, however. A considerable number of these engines 
have been used in the electric lighting service of large cities, 
to which service they were the first to be adopted for driv- 
ing large dynamos directly connected. Under some con- 
ditions, it is found that the weighted governor is too sensi- 
tive, or too much affected by inertia, to give perfect regula- 
tion. For such cases, Mr. Porter has designed an isochronal 
governor, which is free from this cause of variation. 



66 STEAM ENGINES FOR 

Engines of this class have many advantages, consequent 
upon their high speed; they are, other things being equal, 
more economical in the use of steam; they can be given a 
very much smaller fly-wheel; they have, in consequence of 
the enormously reduced weight of wheel, less friction; they 
are more easily held to their speed by the governor; they 
are less subject to variation of speed between beginning and 
end of any one stroke; and they are usually less trouble- 
some and expensive to connect to the load than slow run- 
ning engines. These advantages are common to all classes 
of engines, as they are driven up to high speeds; the class 
here considered is simply better fitted to realize these 
advantages than the older forms of engines, because they 
are especially designed for high speed. The objection to 
the "high speed engine, " is the increased risk of wear, and 
of accident due to their rapid motion, and especially the 
risk, that when accidents do occur, as they will now and 
then in the best regulated establishments, they may be 
vastly more serious than with engines working at ordinary 
speeds. The object of the precautions which are taken by 
builders of fast engines, are all directed to meeting this 
contingency, and to making their machines safe against 
accident. These precautions are seen to be the strengthen- 
ing, and especially the stiffening, of all the parts exposed to 
the stresses due to the action of inertia in the reciprocating 
pieces; the adjustment of all parts to each other in such a 
manner as to avoid spring; the use of the best material; 
an effective system of lubrication; and the securing of the 
most perfect workmanship. 

Watt once congratulated himself that he was able to get 




Buckeye Automatic Engine. 



ELECTRIC LIGHTING PLANTS. 69 

a steam cylinder that only lacked three-eighths of an inch 
of being truly cylindrical; the builder of the "high speed 
engine " of to-day works to the thousandth of an inch, in 
longitudinal measurements, and gets his cylindrical journals 
exact to the twenty thousandth, perhaps to the fifty thou- 
sandth of an inch, a quantity which can be detected by a 
good workman. The contrast illustrates well the progress 
of a century in accuracy of workmanship where nicety is 
required. Such nicety, only, can make a fast running en- 
gine safe; such accuracy does make it safe, and such 
engines now do their work uninterruptedly, year in and year 
out, and are found to require no more than that ordinary 
care which all engines are expected to receive. 

A Porter- Allen engine, from the " Southwark Foundry/' 
supplied power to the Weston, Edison, and the Thomson- 
Houston Electric Light Companies at the Railway Exhibi- 
tion at Chicago, May and June, 1883. 



THE BUCKEYE AND HARTFORD ENGINES. 

THE engine last described was a long time alone in the 
field as a " high-speed engine/' The principle rep- 
resented by its designers was recognized as correct by every 
intelligent engineer, and it was admitted that the fast engine, 
other things being equal, would prove the most economical 
in its expenditure of heat, as well as in its efficiency as a 
machine subject to friction. But builders were not able to 
bring themselves to accept what seemed to them the risks 
incident to high speeds. The pioneer in this new field was 
not altogether successful for a time, and it seemed to be 



70 STEAM ENGINES FOR 

certain at one time, that the engine, despite the pluck, the 
persistence, and the skill of its indefatigable promoter, must 
retire from the market. But no discouragement could quite 
destroy confidence in this engine, which had become the 
embodiment of the most recent phase of progress. Grad- 
ually, one difficulty after another was overcome; parts were 
strengthened and given satisfactory proportions; the mate- 
rials were improved and the workmanship of the machine 
was made as nearly perfect as the best tools, handled by the 
best workmen, could make it. A little gain was seen each 
year, and, after a time, it was seen that the new class of 
' steam engine had " come to stay." 

One of the first engines to come into the field after this 
period of doubt had closed was built by an enterprising firm of 
Western manufacturers. This was the " Buckeye Engine," 
designed by Mr. J. W. Thompson, and built by the Buckeye 
Engine Co., at Salem, Ohio. The engine did not start as a 
radical competitor of the pioneer engine; but it was from 
the beginning, a moderately high-speed engine. It was 
fitted with a positive motion " automatic " valve-gear and a 
balanced valve, and had a stability and an excellence of 
workmanship that made it safe at fast speeds ; while the 
peculiarities of its construction were such as gave it a very 
high place as an economical machine. It was capable of 
meeting in competition the best engines of the day. 

The form given the larger sizes of this engine is seen 
in the preceding Fig. The general arrangement is not 
essentially different from that of the Corliss engine, which 
has been described in earlier articles. 

The cylinder is carried on a pedestal, as is the latter; 



ELECTRIC LIGHTING PLANTS. 71 



the frame consists of a girder uniting the cylinder and the 
main pillow block and carrying the guides; the crank-shaft 
end is carried by another pillow block. The main frame 
is, however, supported by a strut which is now usually seen 
in other engines, and which takes the load tending to spring 
the girder under the guides. The construction of the cylin- 
der, and the arrangement of the valves, is shown in the 
next Fig. 

The live steam is taken into the steam-chest at A, passes 
through the passage, a, a, through the openings, Z>, Z>, into 
the box-shaped valve, B y B, and thence through the ports, 
b, b, into the cylinder, as the ports in the cylinder are alter- 
nately brought opposite those in the valve. The cut-off 
valve is formed of two sliding plates, C, c, connected by 
rods, C , and sliding on seats formed on the inner, or work- 
ing, side of the main valve, so as to cover the main steam 
ports alternately, and at times which are determinable by 
the governor. The stem, g y driving this valve, passes 
through the main valve stem, which is made hollow for that 
purpose. The cut shows the steam entering the cylinder 
at the left, and the cut-off valve just beginning to slide over 
the port, while the exhaust is taking place at the right, past 
the end of the main valve, through the chest, and around to 
the exhaust pipe seen partly dotted at F. At e, e, are seen 
two "relief chambers," which receive live steam from the 
steam valve through holes, f y /, and thus balance the valve 
at a time when the pressure on the seat caused by the then 
excessive area of the balance openings, £>, d (which open- 
ings must be made sufficient in area to produce a slight 
pressure of the valve on its seat when the tendency to lift 



7* STEAM ENGINES FOR 

the valve from its seat is greatest), is overbalanced. These 
holes only fill when this relief is needed. The equilibrium 
rings, Z>, d y seal the joint between the valve and the dia- 
phragm separating the steam-chest, #, #, from the exhaust- 
chest F. 

The governor is of a type that has not been seen in the 
engines previously described. It is shown in the following 
illustration, page 68. 

In the common " fly-ball governor/' the two balls revolve 
about a vertical spindle, to which they are attached by a 
pair of arms in such a manner that they may take any posi- 
tion that the resultant action of gravity, centrifugal force, 
and the pull on the supporting arms may give them. A 
defect common to all governors of this class is that the 
force tending to pull the balls downward is perfectly uni- 
form. Gravity never changes at any one place. The posi- 
tion taken by the balls, at any fixed speed of engine, is 
always the same; the connection of the balls with the regu- 
lating mechanism, is one which always preserves a fixed rela- 
tion between the position of the governor balls and the posi- 
tion of the regulating apparatus. Thus it happens that the 
engine can never be kept precisely at speed, unless the speed 
is such as will give the governor exactly its normal position 
and, at the same time, such that the valves shall supply just 
the normal quantity of steam to the engine. With reduced 
steam pressure, the engine drops to a slightly lower speed, 
and runs at that speed instead of the proper number of 
revolutions; when the load decreases, the engine runs at a 
little higher speed than is intended; and no method of 
attaching that form of governor can give absolutely uni- 




I 

ft 

Q 
g 



o 

H 
u 
w 
c/3 



ELECTRIC LIGHTING PLANTS. 75 

form speed. If, however, we can substitute for the action 
of gravity, a force which can be made to vary with change 
in the position of the balls, in such a way that the variation in 
the opening of the throttle, or in position of the point of 
cut-off, shall go on until the engine comes to speed, irre- 
spective of all other conditions, we shall have what is known 
as an " isochronous" governor, and shall be able to get the 
correct speed, whatever changes occur in steam pressure or 
in load, provided that there is steam enough to drive the 
load at speed with the least expansion for which the engine 
is designed. Such an adjustment can be made by substitut- 
ing the tension of a spring, properly set, for the action of 
gravity. The form of governor here illustrated is, or can 
be made to be, of this class. It simply requires that the 
spring tension shall be given a certain easily determined 
relation to the effort of centrifugal force. 

A governor of this character, when well made and 
adjusted, will open the throttle valve, or will increase the 
ratio of expansion, as the steam pressure diminishes or as the 
load is increased, and will continue to move in the proper direc- 
tion, indefinitely, or until the machine comes to speed, or 
until the engine is doing all that it can do. In the gov- 
ernor here used, two levers are set on either side the crank- 
shaft, in a frame or a pulley to which they are pivoted at 
b y b. These rods carry weights, A, A y which may be ad- 
justed to any desired position by means of the bolts seen 
in the cut. The outer end of each rod is linked to the 
loose eccentric, C y C, by the rods, B, B, and is controlled 
by the springs, F y F, which resist the effort of centrifugal 
force tending to throw the weights outward. As the weights 



7<> STEAM ENGINES FOR 

swing outward or inward, as the one or the other of the two 
opposing forces predominates, the eccentric is turned on 
the shaft in such a manner as to give the valves that motion 
which is necessary to produce the proper distribution of steam 



Governor. 
to bring the engine to its speed. The adjustment of this 
regulator to its work is easily obtained by the shifting of 
the weights along the levers, or by increasing or diminishing 
their amount, as is found necessary. 



ELECTRIC LIGHTING PLANTS. 77 

This governor is adjusted for an engine moving in the 
direction of the arrow. To adapt it to an opposite motion, 
the pins, b y b, are shifted to the other set of arms which are 
shown having bosses for their reception. Wooden buffers 
check the governor at the extremity of its range of motion. 

The range of expansion, as determined by the governor 
in this engine, is from the beginning up to two-thirds 
stroke. 

The engine has many interesting peculiarities of con- 
struction, in its details, which space will not permit us to 
consider. 

The Hartford Engineering Company, who are build- 
ing this style of engine, make a form of bed which is somewhat 
similar to that designed by the makers of the Porter- Allen 
engine, but which is particularly solid and graceful in ap- 
pearance. It is seen on the opposite page.* This 
firm, as well as the original makers of engines built under 
Thompson's patents, endeavor to secure in their engines, 
great weight in the parts in which solidity is important, 
such large area of bearing surfaces as is essential in these 
engines, moderately high-speed of piston and of rotation, a 
steam pressure, usually of about 80 pounds per square 
inch, and adopt a ratio of expansion for their non-con- 
densing engines, of from four to five. Their table of 
powers of their standard sizes is based upon estimates for 
steam at 80 pounds and a cut-off at one-fourth. In con- 
struction, these engines are carefully made with all joints 

* The first designer to carry the line of the steam cylinder along the surface 
of a "box-bed," and thus to secure maximum vertical and horizontal stiffness 
in this manner, so far as the knowledge of the writer extends, was Dr. E. D. 
Leavitfc, Jr., who made such an arrangement in engines, in the design of which 
the writer assisted, as early as 1860. 



78 STEAM ENGINES FOR 

scraped, and all pins, and all journals also, ground with 
scrupulous care. 

The method of regulation is, as has been seen, quite 
different from that practiced by the older standard makers. 
It is subject to the objection, that as the regulator has 
thrown upon it the duty of altering the position of the 
eccentric, the load so brought upon it may make it less sen- 
sitive and less effective in regulating the speed. This con- 
clusion, which is that usually held by the older engineers 
in the profession, seems to be contrary to the fact; although, 
when comparing the older kinds of engines, it is fully sus- 
tained by the superior regulation of the engines of the " au- 
tomatic " class. The fact, now familiar to every engineer 
accustomed to the management of electric lighting ma- 
chinery, that engines having regulators of the class to which 
that under consideration belongs are capable of giving a 
good regulation, even when directly connected to the dy- 
namo, is sufficient proof that such a system of regulation 
may be able to do perfectly satisfactory work. The fric- 
tional resistance of the system, while in motion, is not a 
matter of importance; as in any system in movement, and 
subject to jar, the friction is practically eliminated and 
every part assumes the position that it would take in a sim- 
ilar system free from friction. The action of the resistance 
cf the valve, so far as it is transmitted to the regulator, 
probably acts to hold the regulator fast during the period 
of its action, leaving it free to move into any new position, 
corresponding to the speed of the engine at the instant, 
without hindrance during the remainder of the time. 

All of these fast-running engines will be seen to have 






ELECTRIC LIGHTING PLANTS. 81 

shorter strokes of piston than is customary with the earlier 
types. One reason which has guided their designers to this 
proportion is that the loss by internal condensation becomes 
less as the steam is given less time to discharge its heat, and 
hence high-speed of rotation and short strokes are adopted. 
The best proportion of stroke to diameter of piston, the 
number of revolutions in the unit of time being fixed, is easily 
ascertained by a very simple investigation. It is found to 
be two to one. This is about the proportion generally 
adopted in these engines. Many engines are, however, given 
a ratio of i 1-2 to i. The shorter stroke has the great ad- 
ditional advantage, the speed of piston being the same, of 
giving a less costly engine to build. The proportion is 
sometimes dictated partly by the character of the work to 
be done; thus, in driving the dynamo directly, the velocity 
of rotation must be very great and a short stroke becomes 
advisable — the shorter as the speed is higher. In such 
cases, therefore, engines are often made with even shorter 
strokes than considerations of " efficiency " alone, would 
dictate. 

Reviewing the construction of this engine, it is seen that 
it is distinguished from those which have been already de- 
scribed, by its peculiar balanced valve which can be pro- 
portioned to take any desired part of the steam pressure, 
leaving, if properly adjusted, just enough on the valve to 
hold it with certainty to its seat and to secure a little wear 
to give bearing and fit between valve and seat, that this 
valve is arranged to take steam through, and to deliver 
steam outside, the shell; that it has a system of perfectly 
flat wearing surfaces, and a positive movement of in- 



82 STEAM ENGINES FOR 

variable extent, and thus is not liable to the formation 
of shoulders on seat or valve; that its clearance is so 
small that it is easy to counteract any ill effect, ordi- 
narily due to that cause, by moderate compression; that it 
has two ports and thus possesses such advantages as may 
be claimed for that arrangement; that the governor is driven 
by a positive connection with the shaft on which it is set ; 
that, as the cut-off is adjusted by the motion of an eccen- 
tric, the ratio of expansion is the same at both ends of the 
cylinder and that it possesses the advantage, common to all 
engines having a positive motion valve-gear, of being unre- 
stricted in speed. 

Many of these engines are already in use driving electric 
lighting machinery. 



THE CUMMER ENGINE. 

ALL of the class of engines now under consideration 
have been seen to differ radically from the engines 
previously described (as not well fitted for direct connec- 
tion to the dynamo), and to have a number of character- 
istic points in common which especially fit them for use in 
direct connection. This latter class of engines, however, 
exhibit some differences among themselves which are im- 
portant and very interesting to the engineer and the user 
of steam power. 

The engine last described will have been seen to differ, 
in a very notable way, from that which immediately pre- 
ceded it. The latter had a system of valves that differed 
from the former no less radically than did its system of 
regulation. We have now to study an engine which re- 




The Cummer Engine. "C* 



ELECTRIC LIGHTING PLANTS. 85 

sembles the last in its general features — the use of a cut-off 
valve riding on a seat formed upon or in the single main 
valve, a system original in principle with Meyer, an engineer 
well-known, years ago, in Europe, and the use of the pecu- 
liar form of governor which adapts itself to a position on 
a horizontal or on an upright shaft with equal facility. 
This engine, however, has some curiously interesting and 
ingeniously contrived points of construction which, as well 
as its performance, make it well worthy of attention. This, 
the u Cummer Engine," is illustrated in the engravings to 
be described below.* 

The Cummer Engine Company makes a number of dif- 
ferent forms of engine, using various kinds of valve-gear 
and different forms of regulator and of engine frame; but 
the style with which we are here principally concerned is 
that which is best adapted to driving a load at high speed 
with great economy and with the most perfect regularity. 

The general form of the engine, as shown in the Fig., on 
page 74, is very similar to that of engines already described. 
It has the " girder" frame, or bed, is well supported at each 
end, has a firm and substantial connection in the line of 
thrust and pull between cylinder and crank-shaft, and pro- 
visions for lubrication especially fitted to give safety at high 
rates of speed. A modified form of bed is seen in the next 
illustration, in which one of the engines designed for the 
highest safe speeds is shown. In this engine, the frame is 
made with a pedestal cast upon it directly under the guides 
and extending under the whole length traveled by the 
crosshead, thus giving absolute stability at the point at which 
cross strains are most severe and most productive of injury. 



86 



STEAM ENGINES FOR 



The cylinder overhangs, unsupported, at the back end of 
the frame. No support is there needed, however, as no 
appreciable vertical stress occurs there. This engine has 
the same valve and gear, and the same form of governor as 
is used in the preceding style of machine. In this latter 
form of engine, the crank is replaced by a disc, an arrange- 
ment which enables the builder to effect a more perfect bal- 
ancing of the reciprocating parts than can well be obtained 
with the ordinary form of crank. The rigidity of tfcis form 
of engine is seen to be as essential a feature as in those 
which have been previously described. The box girder 
gives this stiffness in a very satisfactory manner. 




The Cummer Engine. "B." 



The main guides are flat, and are fitted with removable 
faces which can be readily repaired or replaced, when worn 
or "cut," at small cost of time and money. The crosshead 
is a compact, strong casting, having bearing surfaces extend- 
ing well out under the pin, and under the piston-rod socket, 
as well, and it is therefore not likely to cause those awkward 
accidents, due to springing the piston rod at this connec- 



ELECTRIC LIGHTING PLANTS. 



87 



tion, which have proved so costly in less well designed en- 
gines. The gibs which take the wear are removable and 
adjustable. The main bearing is fitted with four-part boxes 
of babbitted cast iron, the side pieces so arranged that they 
may be set out to a bearing as they wear. All the details 
are in accordance with standard practice in this class of 
engines, and description is not called for here. It may be 
safely assumed that this is the case in any successful engine, 
as good workmanship, the best materials, and a strong sys- 
tem of connections, are essential pre-requisites to even the 
beginning of success. 




Cylinder; Steam Valves. 

The valves and the valve-gear of the Cummer engine, 
as has been stated, belong to the " Meyer system" and con- 
sist of a main valve with the cut-off valve riding on the 
back of the main. There is this difference, however, be- 
tween the gear of this engine and others of the same gen- 
eral system : that here we find a separate system of exhaust 



STEAM ENGINES FOR 



valves which are worked independently of the steam valves, 
and thus leave the induction and eduction motions entirely 
free to be adjusted as the designer, the constructor, and 
the user, may desire. The preceding engraving shows the 
disposition of the valves in the cylinder casting, and the 
larger cuts exhibit the method of driving them. The sec- 
tion of the cylinder, above, is made horizontally through 
the steam valve chest, and shows the main valve in section, 
with the cut-off valve riding upon it. At the left is a section 
so made as to exhibit the exhaust valve seat. This is made 
removable. It will be noticed that the valves are of what 
the engineer calls the "gridiron" pattern. They are so 
made, with their several ports, to obtain a free opening with 
small movement and reduced friction of the valve. The 
writer has found this device a decidedly advantageous one, 
and it has been used by some of the most successful design- 
ing engineers of his acquaintance. The more numerous 
the ports, the less the travel required for the valve, the 
smaller the steam chest space demanded, and the less the 
load on valve-gear and governor, usually. 

The next illustration represents the same parts of the 
engine as seen from the side, with valve-chest bonnet re- 
moved at one end, and a section made opposite the supply 
pipe to show the passages and valve-rods. These rods are 
driven by the main eccentric, the steam valves directly, and 
the exhaust through a rock-shaft. The cut-off valve is 
driven by a separate eccentric, as in the preceding form of 
engine, and this eccentric, like the preceding, is adjustable 
in position on the shaft by the governor. The engine is 
thus made " automatic " in its adjustment of the point of 



ELECTRIC LIGHTING PLANTS. 



89 



cut-off, and in regulation. Separate valves are seen at each 
end of the cylinder, and the "clearance" and " dead space" 
is thus reduced to a minimum. This last provision makes 
it possible to " cushion" the exhaust steam up to boiler pres- 
sure on the return stroke, and thus to secure a minimum 
waste by condensation on the opening of the steam valve 
for the succeeding stroke. Cushioning is not here limited by 
the steam side. The construction of the connecting rod, 
and the method of connection, are such that the wear of jour- 



O; 10; \o 

pi -- - (p 

O: Co 

& L ~-vdit±Jo 




Cylinder; Elevation and Section. 



nals and bearings may be taken up, in any case, without 
altering, to any observable extent, the position of the piston 
in the cylinder, and this permits small cylinder clearance, 
also. For the reason above given, the port spaces are 
made no larger than is necessary. 

A comparison of this engine with others of its class will 



90 STEAM ENGINES FOR 

exhibit one very peculiar feature, in which this engine 
stands entirely alone. The governor is carried on a " gov- 
ernor shaft " which is geared to the main shaft, and which 
has no other office than that of carrying the governor and 
the eccentrics. It is evident that so radical a departure 
from standard design must have been caused by the possi- 
bility, actual or presumed, of thus attaining some very im- 
portant result. A little study shows plainly what this 
supposed advantage must be. 

The necessity of providing for efficient performance at 
high speeds of rotation has been seen to have compelled the 
adoption of a positive motion valve-gear; the adoption of 
this gear led to the use of a powerful form of governor, di- 
rectly attached to the cut-off eccentric; this, in turn, compels 
the use of revolving weights, turning in orbits lying in the ver- 
tical plane; this last feature, in turn, again made it necessary, 
apparently,to place the governor on the main shaft, and to meet 
the effort of centrifugal force by a counterbalancing action, 
which could then only be obtained by the use of steel 
springs set in the casings of the governor. But the use of 
springs is considered by many engineers to be so objec- 
tionable, that they would submit to some expense and inconr 
venience to avoid their application, if possible. The objec- 
tions are that they are liable to changes of tension and of 
length while at work, that they never have a definite and 
calculable strength, that they are liable to break in most 
unaccountable ways, and at most unreasonable and unex- 
pected times, and that the adjustment of a balance between 
the two equilibrating forces is often difficult and almost always 
unsatisfactory. These objections undoubtedly do to a certain 



ELECTRIC LIGHTING PLANTS. 



91 



extent exist; but they as certainly are not as serious as is 
often supposed. The writer has had a long experience 




The Cummer Governor Section. 

in this direction, both in the use and in the observation 
of the steel spring for a wide variety of applications, 
and has never yet seen reason to condemn them unre- 



92 STEAM ENGINES FOR 

servedly. The principal objection which can be urged 
against the governor of this class, as usually adopted for the 
kind of engine now under consideration, is probably the 
fact that it cannot be reached while the engine is in opera- 
tion, and that change of speed is thus made impossible 
except by stopping the machine and making changes in the 
adjustment of the springs, then trying the speed again, and 
again stopping to adjust, until the desired speed is exactly 
attained, which disadvantage is shared by the older arrange- 
ment of governor. 

The form of the Cummer governor, which has been de- 
signed to evade these objections to the use of springs, and 
to secure certain special advantages, is shown in the above 
illustration and in that which follows. As has been seen, 
when studying the design of the engine as a whole, the 
governor of the Cummer engine is of the same general type 
as that of the engine last described; but it is mounted upon 
a shaft, separate from, and driven by gearing from, the main 
shaft. The governor shaft also carries the eccentrics, one 
of which is loose on the shaft and is controlled, as to position, 
by links from the weights of the governor as usual. The 
governor is thus enabled to shift the eccentric forward or 
backward and thus by changing its lead, to determine the 
movement of the cut-off valve and the ratio of expansion. 

There is nothing specially remarkable about this part of 
the arrangement. The position of the weights is seen to be 
determined, however, by a system of bell-crank levers which 
connect the middle point of each weight with a vertical rod 
and chain under the engine bed, and on this rod is carried 
a set of weights which may be easily reached when the 



ELECTRIC LIGHTING PLANTS. 93 

engine is running. The bell-cranks within the governor 
casing, move a rod which passes along the centre line of 
the governor shaft and emerges at the left. This rod en- 
gages a large bell-crank at the end of the shaft, through 
which the load suspended under the engine is sustained. 
But one spring, and that a small one, is seen in the whole 
system. The centrifugal action of the governor weights, 
when at the inner limit of their range, is met by the weights 
on the scale pan, and the spring is only required to meet 




The Cummer Governor. 

the additional action of the governor weights when they 
fly outward, as the engine increases speed. The more nearly 
an equilibrium is maintained between the action of the 
flying weights and the balancing load, at the proper speed 
of engine and at all possible positions of the governor, the 
more perfectly " isochronous " does the governor become, 
and the more exactly will the engine hold its speed, under 
all variations of steam pressure and of load. With this 



94 STEAM ENGINES FOR 

governor, the weights on the pan can be increased or 
diminished at any moment, and to any desired amount, 
whether the engine is in motion or at rest; the isochronous 
adjustment can be effected as nearly as desired, and the 
speed of engine may, at any moment be altered, much or little 
as may be advisable. 

This accessibility of the governor, and the disuse of 
heavy springs to control it, are the principal advantages of 
this form of governor. It has also some incidental advant- 
ages which are worthy of notice, although of less import- 
ance. The governor shaft is comparatively small; this per- 
mits the use of very small eccentrics; this reduces friction 
and load on the valve mechanism, and this, in turn, adds a 
little to the efficiency of the engine, as a compensation for 
the introduction of an additional shaft. The one spring 
used here is smaller than that needed for other governors 
of the same class, and is relieved from tension entirely at 
frequent intervals, and the periods of " rest " thus given it 
are likely to insure an increase in its longevity which may 
prove to be a point in its favor worth mentioning. It may 
sometimes, although certainly not frequently, occur that an 
engine may be required to work, at different times, at cer- 
tain different, but fixed, speeds. In such a case, it is easy, 
with this engine, to find a set of weights which when in 
place, will give each one of these fixed speeds; the engine 
can then be, at any instant, brought exactly to either speed 
by hanging on the scale pan the right weight for the speed. 
The several weights can be kept at hand for use as required. 
Such an arrangement may be sometimes especially useful in 
electric lighting. 



ELECTRIC LIGHTING PLANTS. 95 

Several styles of the Cummer engine, other than those 
which have been described, are built for the market. Those 
which have been here illustrated are, however, especially 
fitted for such work as is the subject of this article. Both 
of the forms which have been described are well adapted 
to use in electric lighting plants, and are proportioned for 
high speeds; they are designed for nice regulation and are 
likely to prove durable, economical, and otherwise satisfac- 
tory motors. They are intended for steam pressures of 90 
or 100 pounds per square inch, and their rated powers are 
based upon an assumed piston speed of about 400 times the 
cube root of stroke, as nearly as it can well be reckoned by 
the old method of James Watt — a speed more than three 
times as great as was thought best in the time of that great 
engineer. Even this speed is not to be considered remark- 
ably great for engines designed and built, as are these, with 
especial regard to the requirements of high-speed motors. 
The steam pressures adopted are those generally regarded 
by engineers as, on the whole, the best for ordinary pur- 
poses, and are those beyond which the giin in economy by 
further increase becomes rapidly less with even the best 
engines. The point of cut-off is calculated, in estimates 
of power, to be at from one-fourth to one-fifth stroke, and, 
as a rule, nearer the first than the last figure. The best 
ratio of expansion for any given case is to be determined by 
a comparison of cost of fuel and steam supply with other 
operating expenses, at the place of operation. 

The engine above described has been used, in many cases, 
to supply power for driving dynamos in electric lighting, 
and has an excellent record in that field, as well as in cotton 



9 6 



STEAM ENGINES FOR 



and flouring mills, which demand the most perfect possible 
regulation. 

One of these engines (16x36), at the Cincinnati Exhi- 
bition of 1883, was tested by the committee on electric 
lighting apparatus and found to alter its speed but 2^2 per 
cent., when the whole load, 124 horse-power, was thrown on 
or off; it varied one revolution per minute with a change 
of steam pressure of from 90 down to 50 pounds. 




The indicator cards, of which copies are given above 
as taken from this engine, show the method of distribution of 
steam in engines with positive motion valve-gears, such as 
are here considered as fitted for direct connection with 
large dynamos, and for high speed generally. The illustra- 
tion exhibits a series of indicator diagrams taken from this 
engine at points of cut-off varying from one-tenth to one- 
third stroke. It is seen that the steam lines are as straight 
as those of a drop cut-off engine, very nearly up to the point 
at which the effect of closing the cut-off valve begins to ex- 
hibit itself in the production of the expansion line. The 



ELECTRIC LIGHTING PL A N TS. 9 7 

expansion curve is very nearly that obtained by laying down 
the hyperbolic curve of Marriotte, and the exhaust is as 
clean and prompt as need be desired ; the back-pressure 
line closely follows the atmospheric line seen immediately 
beneath it, and the compression line at the right hand end 
of the card is quite as good as is often seen in the most per- 
fectly proportioned engine with detachable valve. As the 
steam follows further and further, the sharpness of the 
corner between steam and expansion lines gradually be- 
comes less, and the form of that part of the diagram ap- 
proximates that found in the older forms of plain slide 
valve engine. For the most generally desired ratios of ex- 
pansion, however, the form of the curve is satisfactory, and 
it is evident that the adoption of the positive motion type 
of valve-gear does not introduce any very serious loss of 
efficiency in this respect. 



THE STRAIGHT LINE ENGINE. 

T3 EVIEWING what has been said in this section of 
-*- ^- engines capable of direct connection to the dynamo, 
it will be noted that the engines which have now been de- 
scribed have belonged to two classes, differing from each 
other in two very important respects. In the first, repre- 
sented by the Porter- Allen engine, we find a form of engine 
especially, and very ingeniously, designed for high speed of 
rotation, fitted with four balanced valves, with the object of 
securing minimum " dead space," and maximum economy 
and ease of working, and controlled by a governor which 
differs from the older form introduced by Watt, by several 



9 8 STEAM ENGINES FOR 



useful modifications of design, and especially, by being 
loaded in such a manner that its speed, and, consequently, 
its power and sensitiveness in working, are greatly increased. 
In the second class, we find a valve-gear of the Meyer type 
driven directly by the eccentric, instead, as in the first 
class, through a link, and regulated by a governor riding on 
the main or the governor shaft, beside, and directly attached 
to, the eccentric. The features essential to a " high speed " 
engine are also embodied in the second, as well as in the 
first, class of engine. 

We now come to the examination of a third-class of high 
speed engine, which differs as radically from the two pre- 
ceeding as they from each other. In this new form of engine 
we find but a single valve which docs duty both as a dis- 
tributing and as a cut-off valve. A form of engine belong- 
ing to this class, with which the writer happens to be 
familiar, is that known in the market as "The Straight 
Line Engine." 

This engine, so far as it is novel, is the invention 
of, and also is designed by, Professor John E. Sweet, form- 
erly the superintendent of the workshops in which instruc- 
tion in machine work was given in the Department of 
Mechanical Engineering of Cornell University — a position 
in which he became widely known as one of the most skilful 
and ingenious mechanical engineers in the United States- 
later a President of the American Society of Mechanical 
Engineers. The first of these engines was built at Ithaca 
for experimental purposes, by students under the instruction 
of the designer. 

The Straight Line Engine has many interesting and novel 




Straight Line Engine. 



ELECTRIC LIGHTING PLANTS. 



points, which will bear much more extended study than they 
can be given in the small space which can here be allowed 
for the description of the engine. The problem, proposed 
to himself by the inventor, was to design an engine which, 
while consisting of the smallest possible number of parts, 
should, nevertheless, be economical in its use of steam, 
capable of the most perfect regulation attainable with any 
known device, strong and stiff in every part subjected to the 
working strains of an engine working at high speed, inex- 
pensive in first cost, and durable as a simple engine can be. 

This engine is shown in the accompanying illustration. 

A vertical engine, which is shown at the end of the 
article, is also designed for all powers ; there seems no 
reason why it should not prove a good style for heavy work; 
better in some respects, in fact, than the horizontal engine. 

The engine takes its trade designation from its peculiar 
form of frame, which is seen to consist of two perfectly 
straight diverging struts extending from the end of the 
cylinder directly to the two main bearings, thus carrying the 
line of resistance to the pull and push of the connections 
exactly along its own central line. No possible arrangement 
could give greater stiffness with the same weight of material. 
The whole structure is carried upon three points of support, 
#s is the practice with " surface plates," which must, if pos- 
sible, have an absolutely definite and invariable system of 
suports, to avoid the slightest danger of "spring." These 
points are under the main bearings, and beneath the steam 
cylinder. The two journals receive equal loads ; the crank- 
pin is not subject to the deflecting forces met with where 
a crank is overhung ; danger of unequal wear of journals, 



102 STEAM ENGINES FOR 

and of springing the pin, is thus avoided very completely. 
The fly-wheel is placed in twin-form between the main 
bearings, and also serves as crank, thus making the best of 
cranks as well as balance wheel. This position of the bal- 
ance wheel is one of peculiar advantage. By its action at 
this point, it intercepts heavy and objectionable stresses, 
which, in other engines, are transmitted to the main shaft ; 
and the reciprocal action of counterweights and equilibrat- 
ing parts is thus only felt within a mass of metal, which can 
resist them with perfect safety, and without their being felt 
in the more sensitive parts of the machine. This arrange- 
ment renders the main journal less subject to springing un- 
der the loads transmitted through it. To secure better dis- 
tribution of wear, the crank shaft is allowed some end-play. 
This end-play, together with the carefully arranged system 
of lubrication, are the best possible insurance against exces- 
sive friction and wear. 

The steam cylinder has the appearance of the cylinder 
familiar to every one, as seen on ordinary plain slide-valve 
engines. Its valve chest is placed at the end nearest the 
crank, and the ports and passages are carried as in those 
engines. The valve stems have no stuffing boxes, but pass 
into the chest through unusually long and carefully fitted 
holes, in a hub, made about five one-thousandths of an inch 
larger than the rod inside the Babbitt metal bushing, 
for a length of six diameters or more. The hub is 
loose in the hole in the end of the valve chest, and is 
packed at the ends by a washer fitted on a flat seat on the 
inside. The piston-rod is similarly fitted. 

The crosshead is a very long casting which overruns the 




Straight Line Engine. 



ELECTRIC LIGHTING PLANTS. 105 

guide at each end at every stroke, and thus is rendered safe 
against wearing to a shoulder. A pin subject to recipro- 
cating efforts in any part of an engine, whether it rotates, or 
carries a rotating or a vibrating piece, is apt, in time, to 
show wear on the two sides in line with the principal pull 
or thrust, and to lose its cylindrical form. In this engine, 
such wear is avoided at the crosshead pin, by cutting away 
the surfaces, which do little or no work, and thus securing 
overrunning surfaces, which are not subject to this distorted 
wear to so great an extent. Many other minor points invite 
attention, but they cannot be here considered. 

The principal feature of this design, in connection with 
that phase of its work which is of especial interest here, is 
its valve-motion. The valve is a rectangular block, sliding 
between the seat and acoverplate; is shown in the engraving. 
Ports are cut through the coverplate, through the valve, 
and. through the seat into the steam and exhaust passages 
in the cylinder casting, in the proper positions. These ports 
are double at the ends of the valve, and a single port of 
ample area is made through the middle of the valve. 

The valve is what may be called a " piston valve " of 
rectangular section, the space in which it slides having, 
therefore, also a rectangular section, and permitting the use 
of a detached coverplate, which, while sustaining the pressure 
of steam that would otherwise come upon the valve, 
and thus making it a balanced valve, nevertheless allows 
any unusual pressure, occurring when the piston comes 
back to the compression period of its cycle, to raise it, and 
thus to permit the water which may have caused the pressure 
to flow back, and thus relieve the cylinder, and obviate all 



106 STEAM ENGINES FOR 

danger of forcing out the heads. The principal feature of 
this device is not new ; the writer handled such a balanced 
valve on marine engines, rated at above 5,000 horse-power, 
nearly twenty years ago, and found them, so far as his own 
experience went, perfectly satisfactory. This new applica- 
tion of the principle, however, embodies some new and 
interesting points. The valve cover is sustained on loose 
packing strips, which are free to close up upon the edges of 
the valve, and to take up wear as it occurs. The form of 
the plate, its domed top, is such as to give it great stiffness 
against the superincumbent pressure, and thus to prevent 
pressure on the valve itself in consequence of spring in the 
plate, and the ports are so placed as to prevent the cutting 
away of the faces and seats by the rushing currents of steam. 
The valve and cylinder ports are not dressed out ; the 
casting is made so accurately that these edges can be left as 
they come out of the sand without loss of efficiency in the 
working of the valve. 

The valve is driven by an eccentric, the motion of which 
is controlled by the governor, and the connection of which 
with the valve is effected by the peculiar system of linking, 
seen in the preceding illustration. The eccentric is so sus- 
pended from the disc, to which it is attached, that it may 
be thrown across the shaft by the action of the governor, in 
such a manner as to give the effect of the once common 
and well known " Dodd motion." It is carried on a lever, 
which is pivoted at one side of the shaft, while the governor 
rod is attached at the opposite side. The singular positions 
of the eccentric rod and the rockshaft arm enable the 
alteration of the throw of the eccentric produced by 



o 

H 

> 

W 

W 





Straight Line Engine — Governor and Valve Gear. Elevation. 



ELECTRIC LIGHTING PLANTS. iog 

the governor, to be effected without alteration of the 
lead of the valve, so that the steam may be admitted, at ail 
times, at the same point in the revolution of the engine. 
This it does, since the line of the eccentric rod is, at the 
commencement of stroke, in line with the lever on which the 
eccentric is carried. 

The governor is similar, in principle, to those which have 
been described as used on the last type of eagine. It con- 
sists of a single weight, or ball, carried on the end of a lever 
which is pivoted, near its middle point, on one of the arms 
of the governor pulley, and connected to the spring, by 
which it is held under control, by a link extending across 
to the other side of the shaft to the end of the spring, which 
is there secured to the rim of the pulley. The action of 
the governor is substantially the same as that of those which 
have been already described. When the speed decreases, 
the tension of the spring, at the end of the weight lever, over- 
comes the centrifugal effort of the ball, and the latter is 
forced in toward the shaft, carrying with it the end of the 
eccentric lever, and thus giving the valve greater throw, and 
extending the period through which the steam follows the 
piston, producing more power and bringing the engine up 
to speed. The reverse change of speed of engine produces 
the opposite action of eccentric and of valve motion, and 
the cut-off is shortened, and the power of the engine is re- 
duced to that needed to give the correct speed. As this 
governor may be made as nearly isochronal as may be de- 
sired, the approximation to correct speed may be made as 
close as is consistent with the sensitiveness considered per- 
missible. The use of a single eccentric and of a single gov- 



STEAM ENGINES FOR 



ernor ball, and the general simplicity of this combination, 
are especially pleasing to the engineer. They, however, 
include the use of a single valve, and thus restrict the de- 
signer, somewhat, in his adjustment of the steam distribu- 
tion, a restriction which the more complicated forms of 
valve-gear are constructed to avoid, as it is well understood 
that the economy of the machine, in its use of steam, is to 
a certain extent, dependent upon the method of distribution 
of the steam entering, and of the exhaust leaving the cylin- 
der. The main objection is the fact that the mean pressure 
of the steam entering the cylinder up to the point of cut-off 
is necessarily less with a single valve than with the gear in- 
troduced by Sickles and Corliss, and their successors, and 
which have been long standard, and which are admittedly 
superior in this respect. Whether the more costly, but 
more efficient gear shall be used, is to be determined partly 
by the cost of fuel, and must be settled by the judgment of 
an experienced engineer in each individual case. 

The difference in this respect is tiot, however, as great 
as has been by some engineers supposed, and the econom- 
ical value of heavy compression is now becoming so well 
understood, that the general impression in regard to this sys- 
tem of valve motion is becoming considerably and rapidly 
modified. What is lost by the drop of pressure between the 
boiler and the piston, is partly compensated by the variable 
and automatically adjusted compression obtained with this 
kind of motion, as is well illustrated in the action of the 
Stephenson link as used on the locomotive. With this 
arrangement, there is also some loss at the exhaust period, 
but not usually enough to be considered serious. As this 





pq 



-g£E- 



«™IS lii 






ELECTRIC LIGHTING PLANTS. 113 

particular engine is operated, this latter loss, and possibly, 
to a slight extent, the former, are somewhat reduced by 
setting the valve without lead, or even with " negative lead," 
1. e. so that the engine does not take steam until the crank 
has just passed the center, and the piston is starting on the 
forward stroke. 

The engine, as a whole, with all its important parts in 
section, is shown in the above engraving. The unusual 
quantity of material as compared with earlier practice in 
older forms of engine, the excellent distribution of that 
material, the small number of parts, the heavy crosshead, 
the arrangement of fly wheels, and the form of valve are all 
plainly seen, as well as the general arrangement and system 
of connection. The rods and pins, and all running 
parts, are made of steel ; journals are ground to perfect form 
and polished, and the engine, when completed, is set up in 
the shop and carefully tried before sending it out, as is 
becoming the custom with good builders everywhere. The 
designer has made a special effort to reduce friction to a 
minimum, and has given the engine easy running piston and 
crosshead, perfectly formed journals, and a valve gear and 
governor, which are as nearly frictionless as those parts can 
well be made. The growth of the engine into its present 
shape, from the first crude sketches made in 1869, to the 
finished engine and completed type of to-day, and especially 
the gradual evolvement of the governor and valve gear from 
the older forms, would be an interesting subject of study, 
but it cannot here be undertaken. The survival of the fit- 
test, among these devices, has led to the production of the 
engine above described. 

The Straight Line Engine has been frequently applied 



1 14 STEAM ENGINES FOR 



to the driving of electric lighting apparatus. In Pen- 
ney's arrangement of a station of 120 lights, the 
connection of power to dynamo is effected through 
friction clutches, which may, at any instant, be thrown 
out or thrown in ; any two of the engines have ample 
power to drive all three of the dynamos used, and a reserve 
is thus supplied to be used in case of the necessity of 
throwing off one engine for repairs. The current from 
any one generator is capable of being switched into any 
circuit, and all parts are accessible for examination and 
repair. A novel device is that of placing the driving pulleys, 
on the main line, on separate hollow shafts, independently 
supported, to prevent the springing of the line shaft by 
the pull of the main belts. The line shaft runs directly 
through the jack shaft, carrying the driving pulley on 
the line. 

As this engine is adjusted, with large compression when 
at regular speed doing the rated work, with negative lead on 
the valve at that point, becoming positive lead at ^ cut-off, 
it illustrates well the efficiency of the class. A 50 horse- 
power engine, driving a 40 light dynamo, according to 
the report of the manager at the station, ran at 219 revolu- 
tions, and at 220 when 27 lights were thrown off. The 
writer, testing one of these engines rated at thirty-five 
horse-power, using a Prony brake to take up the 
power, counted 233 revolutions, light, and 232, loaded 
with above forty horse-power ; with lower steam, the 
figures became 231 and 230. A well-balanced valve 
and a nearly frictionless governor are the elements giving 
success here. Every good engine, driving dynamos, is 



ELECTRIC LIGHTING PLANTS. 



IIS 



expected to rival this, doubtless, but, doubtless many do 
not. The single-valve engine can evidently, as is here 
seen, be made, by a skilful engineer, to do excellent work. 




Vertical Straight Line Engine. 



i t 6 STEAM ENGINES FOR 



IV. 
Engines Capable of Direct Connection. — {Continued^ 



THE ARMINGTON AND SIMS ENGINE. 

THE engine last described, and that to be here examined, 
are the result of an attempt on the part of their design- 
ers to secure a form of engine which should not only be so 
proportioned and so arranged in the disposition of their 
details that they maybe driven up to the speeds of rotation, 
now so frequently found desirable, without excessive jar, 
serious wear, or dangerous heating of journals, but which 
should also be so simple in plan, so inexpensive in construc- 
tion, and so easy of repair, that the cost of maintenance, 
that great tax upon the proprietor of the average steam en- 
gine, should be reduced to the lowest possible figure. 

In these engines, the possibilities in the direction of in- 
creasing speeds, are sought to be made the most of. Their 
market is not only to be found in the domain of the electrical 
generation of light, and electrical transmission of power, 
but in older fields of work as well. The loss of power in 
the " jack-shafts," or " first motion shafts," of mills and 
workshops driven by the low-speed engines is an item of 
no inconsiderable amount in many cases. The tendency 
is now observable toward the adoption of the high-speed 
engine, even where not quite as economical in the use of 
steam, in direct connection with the main line of shafting, 
through the intermediary of a single belt or pair of gears, 
or even by directly attaching the crank-shaft of the engine 



1 20 S TEA M ENGINES FOR 

engines. The author, in handling naval screw engines of 
short stroke and high speed, has frequently observed this 
fact, and, after a somewhat wide range of experience with 
engines of long and of short stroke, of from 15 to 500 revo- 
lutions, and of powers ranging from the toy engine builr 
during his hours of leisure when a boy in a short jacket, to 
marine engines rated at above 5,000 horse-power, at sea 
and on shore, in the mill and the workshop or on the loco- 
motive, he has never yet seen evidence pointing to any as 
yet nearly reached limit to engine speed, except that which 
is imposed by such conditions as we are gradually and 
steadily modifying, as our knowledge and skill become 
more nearly able to cope with the difficulties which arise in 
our constantly changing practice. 

It will have been observed that, in all the engines which 
have been here described as adapted to direct connection 
to the dynamo and to the " first motion" shaft, some form 
of balanced valve has been used. It has been seen that one 
of the conditions of good regulation by a governor, which 
determines the "point of cut-off," is that the work thrown 
upon the governor shall be the least possible. This con- 
dition evidently points to the use of some expedient, in 
cases in which a positive-motion gear is used, by which the 
resistance to motion of the valve, while a change is being 
effected by the governor, shall be made a minimum; this 
evidently indicates the advisability of adopting some form 
of balancing device. 

The engine to be here described has been designed with 
this end in view, as well as with the idea of securing a form 
of machine which should be simple and inexpensive to 



ELECTRIC LIGHTING PLANTS. 



121 



build, and to keep in repair ; prompt and exact in regula- 
tion under sudden variations of load, and as nearly isoch- 
ronous in its governor-motion, as is practicable. It is of 
the same general class with the last several described forms 




Governor and Eccentrics. — Minimum Throw. 

of engines, but differs from them in its details and in its pro- 
portions, somewhat, and, especially, in the form of its valve, 
and in the devices intermediate between governor and 
valve. In this engine, the "piston" valve is used, com- 
bined with a double port, such as was first used by Allen in 
the locomotive slide valve. These details are illustrated 
further on. The engine, as a whole, will be first described 



STEAM ENGINES FOR 



The accompanying engraving present two perspective 
views of the Armington & Sims Engine, of the styles com- 
monly used in driving electric light machinery. The bed 
is seen to be of the kind already described in the account 
of the Porter- Allen engine, heavy, solid, stiff, yet neat, and 
even graceful, taking the bending stresses of the guides at 
its upper surface, and insured against twisting strains by the 
box form of its section. Two main pillow blocks, in the 
first engine illustrated, carry its steel crank-shaft, and sup- 
port the two wheels, one of which is a balance wheel, and 




Crank-pin and " Wiper." 

the other of which is the pulley, from which the engine is 
belted to its work. The steam cylinder is overhung, and 
the exhaust pipe is carried down below the floor, clear of 
the foundation, which latter has a minimum extent, and 
cost, while amply heavy, and is long and strong enough to 
carry the engine steadily. In some cases, the frame is made 
with but one pillow block, and the crank is overhung ; the 
plan here illustrated is, however, a better one when the en- 
gine is to be driven up to the now usual speeds of such 
machines. 

The journals are all large, and carefully calculated for 
the speeds and pressures adopted. The designers make use 



ELECTRIC LIGHTING PLANTS. 12 5 

of a method of calculation introduced some years ago, by 
the author, which is based on the working of marine and 
stationary engines, under his own management, or under 
his own observation. The drain-pipes for the cylinder are 
fitted as usual, but should be rather larger and more care- 
fully planned, than is necessary where the engine has a 
valve, which may lift from its seat should the boiler at any 
time 'prime" or "foam," and send water over into the 
cylinder with the steam. The provision for lubrication is 
a matter of vital importance in all engines of this class. In 
this engine the " sight feed " is used, in which each drop of 
oil falls through a clear space, on its way to the point to be 
oiled, in full view of the man in charge, and any failure of 
the oil to "feed " is thus promptly detected. The crank- 
pin is supplied by a " wiper " (see Fig.), which takes its 
supply of the lubricant from the oil- cup at every revolution 
of the crank. This device has been used, in very similar 
form, by the author, on fast marine engines, with perfect 
satisfaction, and it is found to work well here. 

The two large engravings show opposite sides of the en- 
gine, and the second exhibits the arrangement of a single 
wheel, and of the steam-chest and valve mechanism. As is 
here seen, a governor, of the same type as that exhibited in 
the articles describing the " Buckeye " and the " Straight 
Line " engines, is secured to the arms of the pulley on the 
nearer side of the frame, and is arranged to adjust the 
position of the eccentrics, which give motion to the valve 
through a rod and valve stem, the connection between 
which two parts is made at a point at which they can be 
conveniently supported by a rockshaft and arm carried at 



126 



STEAM ENGINES FOR 



the middle of the length of the frame. The cranks are, as 
seen in both illustrations, two discs in which the balancing 
mass can be secured at any desired point. The width of 
the pulley carrying the main belt is sufficient to take a belt 
of such breadth, that the stress shall be about 35 pounds 
per inch of its width. The main bearings are made with 
boxes set at an inclination to the horizontal, and provision 




Section of Cylinder. 



is made for taking up wear. The crank-pin is of steel, 
ground carefully to size, as is the universal practice among 
good builders of this class of engines. In this machine the 
main journals are also ground. The distance between main 



ELECTRIC LIGHTING PLA NTS. 127 

bearings is made as small as possible, to permit high speed 
with little risk of springing the shaft. The front cylinder 
head can be removed, when necessary, as shown in the next 
illustration, independent of bed and cylinder alike. 

As here shown in section, it is seen that the cylinder, 
steam-chest and valve-seat are all in one casting, which is, 
however, not a remarkably intricate one. It is best shown 
by the perspective view, while the section next given will 
afford a better idea of the arrangement of the valve. 

The steam-chest, S, S, is in direct communication with 
the boiler, and the valve, which is of the piston form with 
a double steam-port (the second port being seen at P, P ), 
is surrounded by the " live steam," thus taking steam at the 
middle and exhausting it at the ends of the chest, at E, E. 
The valve moves precisely as does the ordinary locomotive 
slide valve, and, as here shown, is just taking steam at the 
piston end of the cylinder, both directly past the shoulder 
of the valve and through the secondary port at the oppo- 
site end of the valve. Thus the steam is introduced, at the 
beginning of the stroke, through a double length of port, 
and hence, with unusual promptness when the engine is 
running at high speed. The consequence is that it gives 
approximately boiler pressure in the cylinder, and through- 
out the stroke up to the point of cut-off, if the steam pipe 
is short and direct, the steam line on the indicator diagram 
is very nearly perfectly horizontal and straight from end to 
end. This is a very unusual feature in diagrams from en- 
gines having positive-motion valve-gear. The form of this 
valve is well shown in the accompanying engraving, which 
exhibits the valve apart from its casing. 



1 2 8 STEAM ENGINES FOR 

All engines of this class will have been seen to be re- 
markable for the shortness of their stroke of piston, as 
compared with the diameter of cylinder. The section of 
the cylinder just given, shows how advantageous is this 
proportion in enabling the port-space to be reduced to a 
comparatively small volume. In the engine of long stroke, 
the port-space becomes seriously large and the compression 
required to fill it introduces a considerable loss both of 
power and efficiency, if the valve-gear used is of the type 
here seen. In fact, it would be probably quite impractic- 
able to secure such a steam distribution as would satisfy 
the majority of engineers, were the engine of long stroke 
and a single valve adopted moved by a link, or by such an 
equivalent for the link as is here used. The total " dead 
space" in these engines, including piston-clearance, is 
sometimes as low as 5 per cent, on large sizes. In all cases 
compression fills this space at every stroke. The piston- 
valve has been often used by earlier builders, but that here 
shown possesses a novelty in the double port. Its advan- 
tages are the ease and cheapness with which it can be made 
and fitted, and with which it can be replaced when worn, its 
perfect balance and ease of working under any practicable 
steam pressure, its permanence, tightness and remarkable 
durability when properly cared for and used with boilers 
supplied with good water. Its disadvantages are, the ra- 
pidity with which it sometimes wears, when it is not kept 
well lubricated, or when it is exposed to the action of steam 
carrying over from the boiler acidulated or dirty water, the 
danger of injury to the cylinder or its heads when priming 
occurs, and the proneness of the attendant to neglect its 



ELECTRIC LIGHTING PLANTS, 



129 



repair when it requires such care These disadvantages 
have sometimes proved to be so serious, as to give many 
engineers a very strong prejudice against the valve ; on the 
other hand, this unfavorable prejudice seems to be now 
giving place to a decidedly favorable opinion, assuming that 
the valve is well made and is to go into good hands, and to 
be used under proper conditions, and these and some other 
very successful makers have definitely adopted the piston 
valve as a feature of their standard designs ; it is even 
coming into use in marine engines of the largest size. In 




Armington & Sims Valve. 



the engine here under consideration, the valve is said by the 
constructors to have proved eminently successful and to 
have proven more durable than their earlier constructions, 
in which they adopted a balance flat valve. It is probably 
too early, as yet, to fully decide what are the exact relative 
merits of the two kinds of valve. In this particular case, 
the removal and replacement of the piston valve can be 
done quickly and inexpensively, and a spare valve being 
kept on hand, it is probable that its use may prove econom- 
ical and satisfactory even where the water used for the 
boiler is not of the best. 

One of the most important, novel, and beautifully ingen- 



! 3 o STEAM ENGINES FOR 



ious details of this engine, is its peculiar arrangement of 
governor and eccentrics. These parts are exhibited in two 
engravings. 

The regulator is precisely the same, in principle, as those 
already described as adapted to the adjustment of the 
eccentric on the main or the governor shaft. It has the two 
weights, t, i, carried on, and forming a part of arms piv- 



Armington & Sims Governor and Eccentrics.— Maximum Throw 

oted to the governor pulley, and revolving in the vertical 
plane as usual in that class of governors. The position of 
these weights, as determined by the speed and the action 



ELECTRIC LIGHTING PLANTS. 1 3 1 

of the springs, determines the position of the eccentrics, C, 
D, and thus the position and motion of the valve, and the 
point of cut-off, flying out and giving a higher ratio of 
expansion as the load on the engine is diminished, or as 
steam pressure rises in the slightest degree, and a lower 
ratio as these conditions are reversed. In the device here 
adopted, however, the valve is driven by an eccentric 
which is " duplex/ ' One eccentric, C, is set inside another, 
D, and connected to the governor arms in such a way 
that, as the weights separate with increasing speed of en- 
gine, both eccentrics are turned on the shaft so as to cause 
their "throws" to coincide, or to separate, as may be 
necessary. When they coincide, the travel of the valve is 
due to a greater total throw, B, and is a maximum ; when 
they are separated as far as possible, the throw becomes A, 
and the travel is reduced to a minimum. The action is 
almost precisely the same as that of a " Stephenson-link," 
worked between full and mid-gear. When the two eccen- 
trics give maximum travel, the action is that of the link- 
motion in full gear ; when they are at opposite sides of the 
shaft, the action is that of a link in mid-gear. By setting 
them at intermediate points, the throw is made that is requir- 
ed to give an intermediate action of the valve, and thus the 
distribution of steam is made to accord with the demands 
of the work by such a variation of the ratios of expansion 
and of compression as is obtained by the link-motion, and, 
in this case, with the advantage in promptness of opening 
and of closure obtainable with a double-ported valve. The 
range of action given in this engine is sufficient to permit a 



1 3 2 STEAM ENGINES FOR 

range of cut-off from o to about three-quarters stroke. The 
lead remains unchanged, and the compression increases as 
the ratio of expansion is increased. 

. The springs of the governor are used in compression. 
The distribution of steam at the usual speed, and with full 
load, is shown by the accompanying illustration, which is a 
copy of an indicator diagram taken from one of the engines 
driving the large dynamos at the Edison station in New 
York city. These engines are coupled directly to armatures, 



Diagram Taken at the Edison Station. 

and make with them 350 revolutions per minute. One of 
these engines was recently kept at work 17 days, making 
over 8,400,000 revolutions without stopping, and then was 
not stopped because of any difficulty with the engine. 
When examined by the author, they were doing their work 
* steadily and smoothly, and were not appreciably affected 
by the sudden changes of load produced by throwing on 
and off any considerable proportion of the lights on the 
circuit. 



ELECTRIC LIGHTING PLANTS, 1 33 

This engine illustrates well the perfection of regulation 
attainable by these positive motion valve-gears attached to 
this form of governor, to which attention has already been 
called. At a trial of engines of this make made by the 
author, to satisfy himself in regard to their action under 
varying load, 25, 50, and sometimes 60 Thomson-Houston 
arc lights were thrown on or off, and the variation of speed 
was but one and two revolutions, respectively, in 280. No 
special preparation or adjustment was allowed in this case, 
and there is no reason to doubt that still closer regulation 
and more perfect isochronism are attainable, if they, at any 
future time, should prove to be desirable. These engines, 
9^ by 12 inch cylinders, had never been before tested, and 
had done no work until started under the direction of the 
author. The lamps demanded very exactly 0.7 horse-power 
each, a fact which indicates that, as connection is there 
made, there can be but little lost power between the engine 
and the lamp. The form of card under load is seen below. 




Diagram Taken by Thurston. 



1 34 STEAM ENGINES FOR 

The success here obtained in the use of a single valve is 
as encouraging as it is remarkable. While it can hardly be 
expected that the economy of this system, other things be- 
ing equal, can be fully up to that obtainable with the more 
elaborate forms of valve-gear previously illustrated, there is 
no question that it is so great that these simple forms of 
engines will be able to find a market in that very wide field 
in which their extreme simplicity of mechanism and their 
moderate cost, as well as their successful operation at high 
speeds, are qualities which compensate any such differ- 
ences in cost of the steam supply. If the same distribution 
of steam, and the same economy is obtained with the one 
form of valve motion as with the other, and if, as is the 
case to a very satisfactory degree with these engines, a cor- 
rect form of indicator diagram can be obtained, it is to be 
expected that the engine will be economical in its use of 
steam. The increasing compression here noted with in- 
creasing expansion is a decidedly advantageous feature, as 
it has an important influence in checking losses by " cylin- 
der condensation" at high ratios of expansion, while also 
reducing the waste due to large clearance spaces, where 
such exist. 

Every engine and every machine of importance, or re- 
markable in any respect, as in such a combination, of in- 
genious devices, effective combination, and efficient opera- 
tion as is here illustrated, is, invariably, the outcome of a 
long period of progressive invention, unintermitted experi- 
ment and more or less steady growth from an initial stage 
to its condition of successful adaptation to the demands 
which it is especially fitted to meet. The Armington & 



ELECTRIC LIGHTING PLANTS. 1 3 5 

Sims engine is no exception to the rule, and its inventors 
and makers, as has been seen, are fortunate in having been 
able to reap so satisfactory a harvest after so long a period 
of growth and ripening. The engine is now built, not only in 
the United States, but in Canada, Great Britain, France 
and Austria. This American engine is in use on many 
foreign steamers, and in numbers of European buildings, 
public and private. It drives the dynamos in the British 
Houses of Parliament. 



* 3 & STEAM ENGINES FOR 

V. 
Fast Engines of Peculiar Design. 



THE BALL ENGINE. 

THE forms of steam engine which have been described 
in the preceding articles have been chosen as being 
fairly representative of what may be termed standard types 
of engine as built by makers of reputation. It will be seen 
that they present to the student of the steam engine several 
distinct forms of machine, each of which is now acknow- 
ledged to be well adapted to produce a certain result in the 
application of heat energy, through the medium of steam, 
to the production of power, and that each is especially fit- 
ted to do its work under certain definite conditions, which 
conditions are less completely met by the others. Each is 
well-known in the market as an engine which has taken its 
place among those which have passed the experimental 
stage and may be relied upon to do good work if well built 
and put in operation under the conditions that it is designed 
to meet. They embody ideas and inventions which have 
grown into form during years of experiment and faithful 
trial and the variety of makes to be found in the market 
belonging to each class, and differing only in the design and 
construction of details, proves that the main principles 
upon which each class is based are well established and 
sound. 

The engines now to be examined are distinguished by 
certain peculiarities of design and construction which mark, 



ELECTRIC LIGHTING PLANTS. 



*37 



in some cases, new departures, in other cases, peculiar ways of 
reaching the end at which more familiar devices were aimed. 
It has been seen that the regulation of the steam engine 
has been found to be one of the most important matters to 
which the attention of the engineer has been called. For 
many purposes, the uniformity of motion of the engine is 
an even more important quality than its economy in the use 




The Ball Engine. 



of fuel, or in all running expenses. A slight change of 
speed in an engine driving dynamo-electric machine will 
seriously injure the value of the light, in nearly every loca- 
tion, and may sometimes entirely destroy it ; a moderate 
variation of speed in the motor of a cotton mill making fine 
goods may break more threads in the spinning department 



1 3 8 STEAM ENGINES FOR 

or do more injury in the weaving room, than would be 
compensated by the difference in economy between the 
most efficient " automatic" engine ever made and the most 
wasteful engine in the market. The principle of regulation 
of the steam engine has been, from the time of the applica- 
tion of the old " fly-ball" governor to the Watt engines of 
a century ago to the present day, that of making the speed 
of the engine determine the amount of steam that shall be 
supplied to it. In the first engines used in the driving of 
machinery, in the old " Albion Mills" erected by Watt and 
his partners in London, in 1786, and for 50 years afterwards, 
the governor adjusted the supply of steam by moving a 
throttle valve. The governor was next arranged to deter- 
mine the point of cut-off by Zachariah Allen, of Providence, 
R. L, in 1834, and by George H. Corliss, in 1849, to adjust 
the trip of his detachable valve-gear. From this latter date, 
it has been the universal custom to so apply it in all engines 
in which uniformity of motion and economy in the expen- 
diture of steam were the controlling considerations in their 
design. The method of accomplishment of this result has 
been seen in the preceding pages, as practiced by Corliss 
and Greene, and by the constructors of positive-motion 
gears which have been the later outgrowth of modern 
changes in the application of steam power. 

Now, after half a century since the grand step taken by 
Zachariah Allen has passed, and a generation after that 
taken by Corliss, a new principle has been introduced into 
the construction of the steam engine, viz., the control of 
the speed of the machine, so far as it is due to the varying 
load, by that variation of load, making the cause of the irre- 



ELECTRIC LIGHTING PLANTS. x 39 

gularity of motion its own corrective, and placing the regu- 
lating principle between the work and the engine in such a 
way that the latter may be made to preserve any given speed 
with perfect uniformity, so far as it depends on the load, or 
causing the speed either to be increased or diminished to 
any desired extent by any given variation of load. 

This idea, like all valuable inventions, has not been the 
result of a single thought or the product of a single brain ; 
it has been floating in the minds of thoughtful engineers for 
a long time. It was proposed to the author, by one of the 
generation of inventors just passed away, years ago ; but, 
in its present form, it became practicable only after the in- 
troduction of the high-speed engine had permitted the use 
of the form of centrifugal governor seen in the engines last 
described. The engine about to be considered embodies 
the first practically useful application of this principle, in a 
practically successful form of engine. 

The Ball Automatic Expansion Engine is the invention, 
so far as it differs essentially from other engines of its class, 
of Mr. F. H. Ball, of Erie, Pennsylvania. In its general 
form and in the details of construction, generally, it resem- 
bles the last two engines which have been described. It 
has a single-valve, positive motion valve-gear, and the solid 
compact structure characteristic of all the so-called high- 
speed engines. The accompanying illustration will give a 
correct idea of its form and proportions. 

The engine bed is of strong and stiff construction, and 
very similar to others with which the reader has become 
familiar. The steam-cylinder is overhung and bolted to a 
faced flange as in the Porter- Allen engine. The main pil- 



T40 STEAM ENGINES FOR 

low blocks are set in the bed of which they form a part, and 
their caps are placed at an angle with the horizontal plane, 
as is sometimes done in marine engines, and less frequently 
in stationary engines. The system of boring the seat for 
the cylinder, aligning the guides for the cross-head, and 
boring out shaft-bearings, here adopted, gives perfect align- 
ment ; and the preservation of the alignment is insured by 
this unification of parts formerly detached. As is the case 
with all good engines, the fitting parts are made to standard 
gauge, and a system of inspection insures good work. Pack- 
ing is dispensed with, and joints are made tight, by securing 
exactly plane, and perfectly smooth, surfaces, at abutting 
points. The wearing surfaces of the valves, and other 
rubbing parts, are scraped to shape and exactness of form, 
by the aid of surface plates. The valve is made tight un- 
der steam-pressure, the form of the valve being such as to 
permit this rather unusual operation. 

The Ball Engine has a short stroke and high speed of 
rotation, ranging as now built, from 7 to 10 inches diameter 
of cylinder, 10 to 12 inches stroke of piston, and making 
250 to 350 revolutions per minute. These proportions are 
adopted, probably, principally with a view to meeting the 
demands of electric lighting. 

The essential and most peculiar feature of the Ball en- 
gine, and that which gives it a place in this little treatise, 
is, as has been already stated, its governor. 

The Ball Governor is, in the main, like the governors 
which have been described as controlling the several engines 
which have been immediately herein before described. It 
consists of a "governor-pulley," from the arms of which 



ELECTRIC LIGHTING PLANTS. 



141 



are swung a set of weights, which are arranged to move in 
the plane transverse to the shaft on which the pulley is car- 
ried. These weights, or balls, are restrained from moving 
outwards, under the influence of centrifugal force, by a set of 
strong steel helical springs, secured, at one end, to the balls, 
and at the other, to the rim of the pulley. Any movement 
of the weights, in either direction, causes a motion of the 




The Ball Governor. 

eccentric, resulting in the alteration of the throw of the 
valve in such a direction, and to such an extent as to bring 
the engine very exactly to speed. To this extent, the Ball 
governor is identical, in its general construction and in its 
principles and mode of action, with those already familiar 
to the reader. To this extent, it is possessed of the same 



142 STEAM ENGINES FOR 

qualities as the others of its class, and it has been seen that 
good workmanship and correct proportions and adjustment 
may give wonderful nicety of regulation. 

To this governor, as commonly built, Mr. Ball adds a re- 
markably ingenious, and singularly simple yet perfect, in- 
vention ; it is exhibited in the accompanying figures. The 
first of these illustrations shows the governor-pulley detach- 
ed from its shaft, and does not show the eccentric; 
it presents only the essentially novel part of the 
device. 

It is seen that, attached to the radius-bar of each ball, is 
a small spring, connecting a point near the fulcrum of that 
lever with the extremity of a strong, peculiarly shaped arm, 
projecting from the hub on the shaft which is seen within 
the hub of the pulley. The governor-pulley is set loosely 
on this inner hub, which latter is keyed fast to the shaft. 
The arrangement is evidently such that, the shaft being 
turned by the engine, the effort must be transmitted 
through the small spring to the weight arms, thence to the 
pulley, and from the latter to the load to be driven, through 
a belt carried on that pulley. The effect of this curious 
disposition of parts is easily seen : Suppose the governor 
to be so adjusted that, at normal speed and under the rated 
load, the supply of steam and the distribution of that steam, 
are precisely correct, as intended by the designer of the en- 
gine. Now, if a variation of steam-pressure should occur, 
the governor at once meets the consequent change of speed 
by a corresponding change of steam-distribution, and the 
variation of speed is restricted to a range, which, if the 
governor is well proportioned and well adjusted, may be 



ELECTRIC LIGHTING PLANTS. 143 

quite imperceptible to the senses, and hardly measurable 
by count. 

This governor here acts like all the others. But, sup- 
pose the steam pressure to be unchanged, and the load to 
vary — we now have a new movement introduced. The 
force exerted in driving the load is transmitted through the 
small springs which are peculiar to this governor, and 
which connect the main shaft to the driving pulley, through 
the governor. The instant that any relaxation, or any in- 
creased tension, is felt here, the relaxation or the extension 
of the springs, so produced, causes a change in the position 
of the weight-arms, and a corresponding alteration in the 
position of the eccentric ; and the steam supply is at once 
readjusted to meet the variation of load. This may be 
done so promptly and so exactly, that, however much the 
load may vary, the speed of the engine remains precisely the 
same. Load may be thrown on and thrown off to any extent 
that may be found desirable or necessary, and the engine 
goes on with its fluctuating task without an instant of visi- ' 
ble change. Should both steam-pressure and load vary at 
the same time, the load.strings set the example of changing 
the steam distribution to meet the new conditions, and the 
governor-springs controlling the balls are immediately seen 
to yield to the effect of the varying steam-pressure, and to 
continue their motion until the flying weights have set the 
eccentric in correct adjustment to give the right speed. If 
the governor is perfectly isochronous, the new adjustment 
meets the case exactly, and the engine runs at the intended 
speed as before. The load-springs may even be so adjust- 
ed that an increase of load may produce a decrease of 



144 STEAM ENGINES EOR 

speed to any desired extent, or, even more commonly and 
usefully, so that an added load may give increased speed. 
This latter is done in some cases when driving electric 
lights, and also in saw-mills, and for other kinds of variable 
work. In the former case, the engine is adjusted to give 
standard speed when driving full load, and to reduce its 
speed as lights are turned off ; in the latter, the engine 
runs at speed while the saw is cutting, and slows down 
when the work is off. 

The next figure shows the eccentric. A is the main ec- 
centric having an elongated shaft opening ; to this eccen- 
tric is attached the arm B, of which the outer end is pivot- 
ed, allowing the eccentric to swing across the shaft ; this 
motion controls the time during which steam is admitted, 
each stroke. This swinging motion is controlled by the 
rotation of the disc, C, in the following manner : The disc 
has a flange, D, on its side, which is eccentric to the shaft, 
and on the inside of this eccentric flange is a ring, E, which 
engages with a stud, F> in the main eccentric. Thus the 
rotation of this disc forward and backward causes the ec- 
centric to swing across the shaft. The disc has a sleeve 
encircling the shaft and projecting through the elongated 
shaft opening in the main eccentric, and on the end of the 
sleeve is a flange nut, G, which holds the parts in place. 
The rotation of the disc is produced and controlled by the 
governing forces ; the centrifugal force of the weights met 
by suitable springs ; and the resistance of the load equilib- 
riated by the centrifugal force of the weights. 

This form of governor is a very safe one, as, should 
breakage of load-springs occur, the engine slows down or 



ELECTRIC LIGHTING PLANTS. 



U5 



stops. The risk of injury of this kind is unimportant, how- 
ever, if the springs are properly made, as the load carried by 
them is insignificant. A 50 horse-power engine, at 300 revolu- 
tions per minute, carries a load of but about 500 pounds on 
each load-spring. If correctly proportionated and made, 
they should endure indefinitely. The endurance of all 
these springs is the greater for the periods of rest frequent- 
ly given them, and for the fact that they are, much of the 
time, under very uniform tension. 




The Ball Eccentric and Connections. 



The practical result of this novel modification of old 
methods of regulating the engine is that the regulation of 
the steam-engine now can be made to cover more than the 



146 



STEAM ENGINES FOR 



simple preservation of a fixed velocity of rotation. It is 
now possible to determine, within certain limits, not only 
what degree of variation from normal speed shall be per- 
mitted, but also what shall be the normal, and if desired, 
varying, speed of the machine, with varying load. It may 
not only be made to run at a certain fixed speed, but may 
be caused either to increase or diminish the speed, accord- 
ing to a fixed, and economically desirable, law. This new 
principle will probably find many applications, although 
such problems have rarely come to the consideration of the 
designing engineer, hitherto. 

The accompanying peculiar diagrams are taken from the 
recording apparatus of the "Moscrop Indicator," an in- 
strument which automatically and continuously records the 
speed of the engine and its variations. Each revolution 
produces a dot, the height of which above the base-line in- 
dicates the speed. The first of the two diagrams is from an 



^^^MM&Mi 



Moscrop Speed Diagram. — Fair Regulation. 



engine of 250 horse-power, fitted with an " automatic cut-off," 
and furnishing power to a paper mill. It is claimed to do 
good work ; but the author has no personal knowledge of it. 



ELECTRIC LIGHTING PLANTS. 



147 



The second is furnished, by the owners of the Ball En- 
gine, as illustrating fairly an equally trying case. The 
author has other cards of this kind which, with great varia- 
tion of steam-pressure, nevertheless are very smooth, al- 
though not as smooth as that here reproduced. They are 
also interesting as showing how useful a recording speed- 
indicator may be. Such records are more satisfactory, in 
comparing speeds of engines, than are even the best of 
counters, and vastly more satisfactory than counting by the 
watch, as they exhibit the rate of each revolution, together 
with the variation of rate for extended periods of time. 



MoscrOp Speed Diagram. — Ball Englne. 

This engine, with its novel governor, is one of the most 
interesting products of mechanical ingenuity that has been 
seen since the days of Watt. It will probably have but 
little influence on the vitally important matter of steam- 
engine efficiency, as that term is customarily applied, that 
is to say, upon the economy of the engine in consumption 
of steam and of fuel ; but it will undoubtedly, in many of 
its applications, be found to have a very important effect in 
adapting the engine to its work, and upon its efficiency in 
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STEAM ENGINES FOR 



THE IDE ENGINE. 

THE engines which have been described are by no 
means the only engines which are deserving of 
mention, and of careful study, as illustrating the peculiari- 
ties of the best modern practice in the field which it has 
been the object of the author to explore. A number of 
other engines, of one or another of the classes which have 
been described and illustrated in the preceding articles, 
have nearly or quite equal claims for consideration. Of 
these engines, only typical or representative examples have 
been sought, and have been selected from the machines 
with which the author is most familiar. One more engine may 
be here described — not as possessing the singular novelties of 
design which distinguish some of those already examined* 
but as affording a good illustration of the principles and 
practice which have come to be recognized as distinctive of 
the latest phase of that progress, which has recently been 
so rapid, in the direction of improved methods of con- 
struction, as well as of design, and in the application of the 
modern materials of construction. The engine is one with 
which the author cannot claim that personal familiarity 
which has led, in some cases, to the selection of those which 
have been previously considered; but a description, such 
as is to be here given, will show that it may fairly be taken 
as a representative of the best practice, in matters of detail, 
which it is the special object of the writer now to exhibit. 

The Ide Engine is of the same class with all the engines 
described in the preceding section — a high-speed engine, 
intended to be driven up to high power and to occupy 
small compass; to regulate with all the accuracy desired in 



ELECTRIC LIGHTING PLANTS. 



U9 



electric lighting, and in the spinning of fine cotton; to have 
good wearing qualities, and to be economical in its use of 
steam and of fuel. The illustrations exhibit its general 
form, and the more important details of the machine. 




Examining it in some detail, it will be observed that the 
frame, although of novel design, is of the same general form 
with those which have been already described in this class, 



150 



STEAM ENGINES FOR 



possessing that solidity and rigidity that have been seen to 
be an essential feature of all successful high-speed engines. 
The main pillow-blocks are formed in the frame; and the 
cylinder is secured at the opposite end, overhanging as in 




cases already familiar to the reader. The crank-pin is set 
in a disc, which permits counterbalancing, and gives great 
strength. The connecting-rod is tapered from the crank- 



ELECTRIC LIGHTING PLANTS. I 5 1 

in to the crosshead-end, in the manner now common to 
all fast-running engines. The outlines of all visible parts 
indicate strength and stiffness, and are very neat in design. 
The valve-gear and governing mechanism are shown best 
by the view of the opposite side of the engine, given in the 
next engraving. The piston-valve is adopted, and is placed 
directly under the steam-cylinder. This arrangement per- 
mits most complete drainage of the cylinder, and thus less- 
ens the danger of accident, should the entrance of water 
with the steam occur to any serious extent. The placing 
of the valve at the side is not an unusual feature of this 
class of engine; but the arrangement here adopted is, in 
this respect, still more advantageous. This arrangement 
also affords a means of getting an equalization of the travel 
of the valve relatively to that of the piston, which is an ad- 
vantage. Still another advantage is that this position of 
the valve-chest gives dry steam from the steam-chest, by 
causing it to act as a trap, as well as drains the cylinder of 
water that may have condensed within it. The connection 
with the steam pipe is made above the line of connection 
between the steam-chest and the cylinder, and it is thus 
rendered possible to remove the former, and get at the 
valve without disturbing the steam pipe. 

The regulation is effected by a governor of the class 
adopted in all engines of this kind, and the regulation and 
the action of the valve are similar in character and in pre- 
cision to those seen in engines already described. The range 
of power, and the distribution of steam at various points of 
cut-off, are shown very beautifully in the indicator diagram 
here given, which was obtained by suddenly throwing off 



T-2 



STEAM ENGINES FOR 



the load; each revolution gives a distinct "card." Steam 
may follow from the beginning nearly to the end of stroke, 
with good exhaust and an excellent range of compression. 
The speed of engine was here 225. The card was taken by 
loading the engine to its maximum power by a Prony 
brake, and then taking the diagrams while the governor 
was adjusting the steam supply, the brake being at the mo- 
ment released. The smallest card is therefore a " friction 
card." The smoothness of action of the regulating mech- 
anism is shown by the uniformity with which the power falls 
off and the cards diminish in area. 




Series of Indicator Diagrams. — Ide Engine. 

The next diagram shows the range of work which such 
engines are capable of doing, and illustrates very finely the 
change in the distribution of steam which takes place in 
this accommodation of the power of the engine to its load. 
It is seen that the compression, as well as the expansion, 
gradually changes in amount as the power varies, both act- 
ing to reduce the area of the diagram with diminishing 



ELECTRIC LIGHTING PLANTS. 1 5 3 

power, or to increase it as the required power beccmes 
greater. A very interesting effect of this change is to give 
increased economy in the use of steam by checking cylinder 
condensation, the greatest known source of waste of heat, 
just when that loss becomes most serious in both absolute 




Indicator Diagram. — Ide Engine. 

and relative amount. In some cases, the economy obtain- 
ed, with considerable expansion, by the introduction of 
large compression, has amounted to above 10 per cent. 
Where superheating is adopted, this gain is less; but in the 
usual case, using saturated steam, the use of the valve- 
motion, of which an example is here illustrated, brings with 
it a very important advantage; and nearly all builders of 
such engines are now agreed in testifying to its value. The 
lines of indicator diagrams obtained by the author from this 
engine are unexcelled by any that he has yet seen from 
engines of this class. 

One very important feature of recent progress in the con- 
struction of the steam-engine is well illustrated in the Ide 



1 54 STEAM ENGINES FOR 

Engine, and affords a special reason for studying it; this 
is the extensive use of steel in its running parts. Within 
a few years it has become possible to obtain from the mak- 
ers of Bessemer and " Open Hearth," as well as of crucible, 
steel, a quality of metal which earlier could not have been 
obtained at all. This is a steel which is distinguished, 
chemically, by its low percentage of carbon and its rela- 
tively high proportion of manganese, and physically, by its 
wonderful combination of ductility and strength. As the 
proportion of carbon decreases in steel it loses strength; 
but it gains ductility and malleability in a far higher ratio, 
and thus it happens that the softer qualities are much bet- 
ter fitted for use in machinery than are the very best of 
wrought irons produced by the ordinary process of pud- 
dling. The former are strong, tough, amply hard for all 
such uses, and perfectly homogeneous; the latter are less 
tenacious, often not as ductile, and are never homogeneous; 
but are full of " cinder streaks," and have a fibrous struct- 
ure that is objectionable, and is never seen in steels. 
These steels are all made by casting molten metal into in- 
got moulds, and thus securing comparative freedom from 
cinder and defective structure. 

The soft steels are displacing iron in every direction; 
and the probabilities seem to be that in the course of time, 
in the coming "Age- of Steel," iron, puddled as is now us- 
ual, will be entirely displaced by these, properly so-called, 
"Ingot Irons." The Ide Engine, as well as other engines 
now coming into market from the shops of the best build- 
ers, illustrate this change of material. It has its piston-rod, 
its connecting-rod, its valve-stems and links, and its smaller 



ELECTRIC LIGHTING PLANTS, x 55 

journals, all of steel. Large castings are not usually made 
in steel in this country, but all small parts are coming to be 
made in that remarkable metal. 



ENGINES OF THE NEW YORK SAFETY STEAM-POWER CO. 

In the course of the somewhat extended series of descrip- 
tions of standard forms of engine which is now soon to be 
closed, it will have been observed that the tendency has 
been toward the reduction in number of parts, and increas- 
ing simplicity of mechanism as the speed of engine is in- 
creased. The earlier types of engine having detachable 
cut-off apparatus as a part of the valve-motion were engines 
of moderate speed of piston and of comparatively long 
stroke, and, therefore, of even more moderate speed of ro- 
tation. The latter forms of standard engine are of simpler 
construction, and of higher speed of piston, and of much 
higher speed of rotation. This difference is not only due 
to the necessity of reducing the number of parts and secur- 
ing greater positiveness of action in the valve-gear, but it is 
also due to the more general recognition of the fact that 
economy of steam and fuel consumption is but one of the 
economies to be studied in the use of steam as a motive 
power, and that the cost of securing great economy of steam 
and fuel may be such as to more than compensate the sav- 
ing effected by such expenditure. This is especially true of 
small powers, and common experience has shown that it is 
seldom advisable to construct complicated valve-gears for 
such engines, as the cost rarely comes within the commer- 
cially economical limit. This principle has probably been 
carried too far; and the author has no doubt that engines of 



I S STEAM ENGINES FOR 

the higher grade may be often found commercially econom- 
ical for even very small powers. The field for the simpler 
class of small engine, nevertheless, is enormously extensive; 
and the number annually built is very great. 

But little attention, comparatively, has been paid to the 
design and construction of small steam-engines until very 
recently. The engineer has been too often inclined to look 
upon this as too small a matter to demand the thought and 
the time that he has freely given to larger and more at- 
tractive work. It is now different, and some excellent 
forms of small engines are to be found in the market. It 
is the intention of the author here to describe a single ex- 
ample of this class of machine, not as the only good engine 
of the class, but as a type of this class. 

The British builders of portable and agricultural engines 
were the first to develop the art of steam-engine design and 
construction in this department. A dozen years ago, they 
were building engines of as little as 20, or even 10, horse- 
power, which demanded but 3 pounds, and even less, of 
coal per horse-power per hour. As early as 1867, they 
reached the figure 4.13 pounds;* in 1870, it became 3.73, 
and, in 1872, the Reading Iron Works built an engine of 20 
horse-power which, on trial at Cardiff, required but 2% 
pounds of picked coal per hour and per horse-power. This 
engine had a cut-off valve on the back of the main valve. \ 
Single valve engines have never done as well; but some of 
them have nearly approached these figures. A consump- 
tion of 5 pounds of coal per hour and per horse-power is a 

* Mechanical Engineering at Vienna; Reports on the Vienna Exhibition: R. 
H. Thurston, Washington, 1878. 
t Ibid., page 100. 



ELECTRIC LIGHTING PLANTS. 



*5 r 



good figure, and is rarely attained in such small engines. 
The best of them may be expected to use from 5 to 7 
pounds and to consume, therefore, from 40 to 60 pounds of 
steam, averaging perhaps about 50, on the basis of the in- 
dicated power. 

Among the earliest of American engineers to turn atten- 
tion to this department of mechanical engineering, were 
Messrs. Babcock & Wilcox, who have become well known 
as the inventors of a successful form of "sectional" steam 
boiler. The style of engine which was designed and intro- 
duced by them, and built by the New York Safety Steam 
Power Co., has now become as generally accepted as stand- 
ard among builders of small engines as has the Corliss en- 
gine among constructors of drop cut-off engines. It has 
been copied in all parts of Europe, as well as in the United 
States. This may be taken as representative of the best 
methods of construction in this country, and as exhibiting 
the elegance in proportions, and that excellence of material 
and workmanship, which are now becoming recognized as 
desirable in steam-engines of even the smallest size. In 
fact, as has been seen, the opportunity here offered for im- 
provement, and for economizing steam and fuel consump- 
tion, is much greater than with large engines; and these 
excellencies are, therefore, the more desirable. 

The engraving exhibits the form of the engine here to be 
described. It is a "vertical engine" mounted upon a base- 
plate of neat and strong form, and with the steam-cylinder 
bolted by the lower head to a very strong and very graceful 
frame. The main journals are carried in bearing construct- 
ed in the frame, and consequently free from liability to loss 



i 5 8 



STEAM ENGINES FOR 



of perfect alignment, or to unequal wear. The valve is 
either a plain, locomotive-slide, or, preferably, a piston valve. 
The latter is fitted in a detachable seat, which can be 
easily removed for renewal of seat and valve, should acci- 
dent or wear ever make it necessary. 




N. Y. Safety Steam Power Co.'s Engine. — 5 h. p. 

The vertical position of the engine prevents wear within 
the cylinder becoming serious or un symmetrical. The 
pistons are hollow, and are packed with rings set with suf- 



ELECTRIC LIGHTING PLANTS. 



*59 



ficient spring to keep them up to a bearing. The cross- 
head, which is shown in the following engraving, has its 
gibs turned to fit the guides in the frame, which latter are 
part of the casting of the frame and are bored out in line 
with the cylinder, and cannot possibly get out of line. 





Crosshead. 

Crosshead. 

The engine above illustrated is of small size — 4 or 5 
horse-power — and has been especially designed for electric 
lighting purposes. The governor is that known as the 
"Waters Governor;" it regulates by adjusting the supply of 
steam passing to the engine through a throttle valve — a 
method which seems to have been here more successful 
than is usual in engines having to perform so exacting a 
kind of work. The speed of this engine is usually about 
250 revolutions per minute. 

Larger engines of this style are often constructed ranging 
up to 100 horse-power. The heavy engines, when of 15 to 
100 horse-power, are given an independent crank-shaft 
pillow-block and a counterbalanced disc-crank. In these 
engines, of all sizes, the modern innovation of the use of 
steel for running parts is very generally introduced. The 
rods, pins, and minor parts are of this metal; the bearings 



1 60 S fEAM ENGINES FOR 

are usually of bronze lined with Babbitt metal, and are 
given large area. Crank-shafts are either of steel or of 



10 H. P. Vertical Engine. - N. Y. S. S. P. Co. 
hammered iron. As is customary with all well con- 
structed engines, these engines are set up and operated in 
the shop long enough to exhibit all defects and to afford 



ELECTRIC LIGHTING PLANTS. 



161 



opportunity to make all adjustments before sending them 
out, and are thus made safe against those annoying delays 
which otherwise atterfd the introduction of such machines. 
The parts are made to gauge, and therefore interchangeable; 
and it is thus made easy to replace them when worn or in- 
jured, at minimum expense and with little delay The 




Semi-Portable Engine. 



valves, and their seats, even, when worn, are taken out, sent 
to the shop, and the spare valve and seat, already fitted 
takes the place of the parts removed. 



1 6 2 STEAM ENGINES FOR 

Where engines are of large size, they usually have the 
engine room and boiler room distinct; with these small 
engines, however, it is found often to be desirable to place 
engine and boiler side by side, and even upon a common 
base, as is illustrated by the last of the preceding engravings. 
This forms what is known, frequently, as the "semi- 
portable " engine, to distinguish it from the "portable," 
which last named style is mounted on wheels. 



THE ERICSSON AND WESTINGHOUSE ENGINES. 

ALL of the engines which have been considered in the 
preceding articles are of one general type — that 
known as the "double-acting reciprocating engine." Before 
the time of James Watt, the only engine in extended use, 
even in the limited field in which the steam engine was then 
employed — that of pumping water from mines — was a "sin- 
gle-acting" engine — the Newcomen engine, which had then 
almost entirely superseded the so-called engine of Savery. 
Watt invented, first, the separate condenser, and then the 
double-acting engine, thus increasing the power of the ma- 
chine and rendering it, at last, applicable to the turning of 
a crank and the driving of machinery and mill-work. In 
the " single-acting engine," the steam drives the piston in 
but one direction, and the return stroke must be made 
without the production of useful work. In the " double- 
acting engine," the steam acts upon the piston in both di- 
rections, and with practically equal effect. Thus, a more 
regular action is secured with a given weight of balance 



ELECTRIC LIGHTING PLANTS. Y b? 

wheel, or the same regularity with a wheel of one-half the 
weight of that required for the older form of engine. This 
smoothness of motion is, in such work as is here considered, 
one of the most essential features of the best steam engine 
economy. At the speeds which have been now attained, 
however, the inertia of moving parts becomes so great that 
moderate variations in the impelling power become com- 
paratively insignificant, and have no perceivable effect upon 
the smoothness of revolution of the crank-shaft. 

The double-acting engine evidently possessed greater 
power than its predecessor, when of the same size, and the 
" efficiency of the machine" was correspondingly increased. 

The very conditions which have been thus made to aid 
in securing regularity have, however, introduced a new dif- 
ficulty: At every revolution of the engine, the crank 
"turns the centre" twice; and, at every passage of the 
centre, the direction of pressure upon the crank-pin is re- 
versed, thus producing a shock which is proportional to the 
difference of pressure, the suddenness with which it is felt 
at the pin, and the extent of the "lost motion" between 
the pin and its bearings. Some lost motion must always be 
permitted here, to avoid danger of heating of the journal 
and injury to the machine. The counteracting adjustments 
are found to be, usually, the utilization of the inertia of the 
reciprocating parts, as in the Porter- Allen engine; the 
adoption of heavy compression, as in the several engines 
afterward described, and very careful adjustment of the fit 
of the brasses on the pin. With the skilful use of these 
expedients, and with the introduction of a perfection of 
workmanship, and of such qualities of material, as have 



;64 STEAM ENGINES FOR 

never before been seen, the " high-speed engine " has been 
made successful at as high as 400, and even, in some cases. 
600 revolutions per minute. The lower of these figures may 
be taken as that representing the maximum in standard, and 
usually best, practice. 

But much higher speeds than these are sometimes de- 
manded; and engines must, in the future, be built to run, 
regularly, steadily, and safely, at, probably, very much 
higher velocities. This may, ultimately, lead to radical 
changes in the design of the now standard forms of fast en- 
gines. Nevertheless, the limit of speed has by no means 
been reached, even at the higher of the above speeds, with 
the common type of engine. The speed of even 450 times 
the cube root of the length of stroke, now a common figure, 
and three times that given by James Watt's rule, is occa- 
sionally greatly exceeded. Captain Ericsson designed an 
engine, some three years ago, for the electric lighting ap- 
paratus of the Delamater Iron Works, which has now been 
running, every evening for two or three years, at 1,250 
revolutions per minute, without giving the slightest trouble, 
or meeting with the most insignificant accident. The pis- 
ton speed is about twice that of the average " high-speed M 
engine, and six times that adopted by Watt. It is probably 
the highest speed ever attained by a reciprocating engine 
doing work for which it had been designed. 

The object of the inventor was to design a steam engine 
for the special work of driving small dynamo electric ma- 
chines, and hence to secure great stability and strength, a 
minimum number of parts requiring lubrication, and abso- 



ELECTRIC LIGHTING PLANTS. 



161 



lute certainty that the parts retained should be, at all times, 
thoroughly supplied with the lubricant. The engine is 
therefore made a " half trunk " engine, the trunk, F, F y 
serving as an oil reservoir. The joint in the eccentric rod 
is provided with a piston moving in a cylindrical guide, 
N y which is also an oil reservoir. The cylinder, C, and 
base-plate, B, are in one casting, upon which is set the 




The Ericsson Engine. 
hollow frame supporting the crankshaft, Zf, Fy and balance 
wheel. Every journal and rubbing part has an oil reser- 
voir and special provision for effective lubrication. The 
whole engine is a model of the product of that most efficient 
kind of ingenuity which seeks definite ends by the most 



1 66 STEAM ENGINES EOR 

simple and directs means. Its performance leaves nothing 
to be desired. 

The limits to velocity of piston and speed of rotation 
have, from the beginning of steam engine practice, been 
thus gradually set farther and farther back; and one 
after another of the limiting conditions have been suc- 
cessfully met and overcome. The earliest limit was that 
found in the bad workmanship and material which Watt 
and his contemporaries encountered, and which gave rise 
to heated journals at even what would now be considered 
very low speeds, and at very small powers. This defect 
being gradually overcome, the next, and a comparatively 
modern, difficulty was found in wear, and the " pound," 
which took place when the lost motion of journals in the 
line of the connecting rod was taken up, at the passing 
of the centres. This difficulty was met in two ways, as 
already repeatedly stated — by making use of the inertia 
of the reciprocating parts, as was done by Porter and 
Allen, and by heavy compression as is practiced in nearly, 
or quite, all of the high speed engines of to-day. The 
first method can be adopted only when careful propor- 
tioning, after calculation, of the weights and velocities of 
the moving parts, has determined the proper weights of the 
compensating pieces. The latter adjustment may be made 
either by calculation or by experimentally finding the com- 
pression giving smoothest running. This effect of increas- 
ing compression can be most satisfactorily seen in the ma- 
rine engine, in which, whatever the speed of the machine, 
and whatever the steam pressure, or however loose the 
journal, the link may be raised so as to gradually check the 



ELECTRIC LIGHTING PLANTS. 



167 



pounding at the centres, and finally to eliminate it altogether, 
the engine often being thus brought to work silently and 
smoothly at speeds far above those which, without compres- 
sion, would be very troublesome, if not absolutely danger- 
ous. This is an experiment which the writer has repeated 
on many engines, and almost invariably with the same satis- 
factory result. 

Some lost motion must always be permitted at the crank- 
pin, and these expedients are usually found to meet the case. 
They probably have their limits, however. There comes a 
time, as speeds are increased, when the weight of running 
parts, as calculated for strength only, becomes as great as is 
desirable to effect the compensation by their inertia ; there 
comes a time, as compression is increased, when the "cush- 
ioned" steam is carried up to boiler pressure, and this would 
seem the natural limit in this matter. The next device, 
chronologically, adopted by the engineer, is that of prevent- 
ing the lift of the brass of the crank-pin and of the cross- 
head pin at the turning of the centres, while still leaving the 
freedom of fit required to give safety from heating. This 
last expedient is that which has led to the construction of a 
class of engines which are as peculiar and as typical as either 
of the classes which have been already described. 

THE WESTINGHOUSE ENGINE 

belongs to this new class, and is here taken as its represen- 
tative. The change of construction characteristic of this 
type of engine is a return to the original " single-acting" 
plan of engine. This has been often proposed, and not in- 
frequently attempted ; but the success attained has not, as 
a rule, been satisfactory. Two, and three, and four, cylin- 



i68 



STEAM ENGINES FOR 



ders have been tried, in the endeavor to secure regular mo- 
tion while taking steam only on one side of the piston ; very 




The Westinghouse Engine. 



high speeds of revolution have been attained ; but the cost 
of steam has been found too great, and their use has not 
become general. The Westinghouse engine has proved it- 



ELECTRIC LIGHTING PLANTS. 169 

self to possess the elements of commercial success, and is, 
therefore, to be taken as illustrating what can be done in 
this direction, by good designing and good business man- 
agement. 

It is evident that, if steam pressure comes upon but one 
side of the piston, the engine can pass its centre without 
the brass lifting clear of the pin, and thus may be driven 
up to any speed without liability of injurious pounding. 
For enormously high speeds, as the engineer of to-day 
looks upon them, this is evidently the type of engine to be 
looked to for smooth and successful working. The illustra- 
tions show how, in the Westinghouse engine, this end is 
reached. The engine has two cylinders, A, A y fitted with 
single-acting pistons, Z>, D, forming trunks filling the bore 
of the cylinder, giving a long steam-tight bearing, and taking 
the connecting-rod pin, A y B, at a point at which no tenden- 
cy to rock the piston can be produced. The top of the 
piston is cored out to prevent transfer of heat from the 
working to the non-working end. The rods, F y F y take 
hold of the crank-pins within an enclosed chamber, C, form- 
ing part of the engine frame, £, C. This frame and bed- 
plate also acts as a reservoir for oil lubricating the journals 
and pistons, which oil floats on water and is dashed up over 
the moving parts so enclosed, at every revolution of the 
engine. No other attention is required than to keep a sup- 
ply of oil in the chamber, by filling as loss occurs by leak- 
age. In fact, the whole engine is thus shut in by its frame, 
and its working parts are invisible, while working — an 
arrangement at once a means of security and convenience. 

The valve adopted in the Westinghouse engine is a piston 
valve of the class already described, but having some pecu- 



iju STEAM ENGINES FOR 

liarities specially adapting it to its use in this engine. Its 
guide, y, is a piston traversing a cylinder separating the 
exhaust space from the chamber below. This one valve, V y 
distributes steam to both cylinders, the two cranks being set 
directly opposite each other. This adjustment of the cranks 
also gives a perfect balance of reciprocating parts, and se- 
cures smoothness of movement of the whole machine, what- 
ever speed may be adopted ; and exceptional speeds of 1,000 
revolutions, or more, per minute are reached without obser- 
vable vibration. 

The governor, /, and its action, are precisely like the same 
parts in the engines described in several of the earlier arti- 
cles. It actuates the eccentric, and determines the point ot 
cut-off by varying the throw of the valve, while retaining 
the lead. The governor is usually so adjusted that it will 
not come into play until the engine falls i per cent, below, 
or rises i per cent, above, the normal speed ; its full traverse 
is effected, also, within this range, the intention being that 
the speed shall never vary more than i per cent, from that 
fixed as its proper velocity. The range of expansion is 
from o to about 5-8 stroke. 

One of the dangers to which fast running engines are 
peculiarly exposed is that of injury by the entrapping of 
water in the cylinder, and the plunging of the piston 
against the mass of incompressible fluid which then fills the 
clearance spaces. In this engine, in addition to the relief- 
cocks, or valves, which are always fitted to such engines, a 
safeguard is introduced in the form of what engineers are 
accustomed to call the " breaking-piece, " a part which is 
made purposely weaker than other portions of the machine, 
exposed to a common danger, so that this piece may go 



ELECTRIC LIGHTING PLANTS. 



173 



when danger arises. This piece is always one the replace- 
ment of which will give little trouble, and make but little 
expense. In the Westinghouse engine, such a breaking- 
piece is made to form a part of the cylinder head. This 




The Westinghouse Engine. — Cross Section Through Valve. 

may be knocked out without injury occurring to any impor- 
tant, or costly, part of the structure.* 

* The writer planned an enerine, about the year 1860 in which the whole 
cylinder-head was made a safety valve which could lift and discharge the water 
into the chamber behind it, the cover of the latter being: bolted on, while the 
cylinder-head was only held in place, against a faced joint, by steam pressure. 




III. 'III. I 'll,' % ■ 

The Westinghouse Engine.— Section Through Shaft. 



i 7 4 STEAM ENGINES FOR 

This breaking-piece is intended to yield at a safe pres- 
sure — 200 lbs. per square inch — and thus save the engine. 
The workmanship on these engines, so far as the writer has 
been able to examine it, is excellent ; and the material of 
the best. These are, however, as has been stated, absolutely- 
essential features of every good high-speed engine. The 
engines are, when finished, set up in the shop and tested up 
to their rated power, before sending them out ; and it is 
thus made certain that they are in good order and in cor- 
rect adjustment. The ingenious and novel methods of se- 
curing certainty of lubrication, in this engine, the constant 
direction of the actions tending to produce heavy strains, 
the small number of parts subject to wear and to breakage, 
the remarkable success met with in the attempt to reduce 
the labor of attendance and cost of maintenance, and all 
other costs causing reduction of commercial efficiency ; the 
compactness, solidity, steadiness, safety at maximum speeds, 
and general effectiveness of this engine, are such as to make 
it one of the most interesting examples of the steam engine 
of to-day that has yet attracted the attention of the engineer. 

The economy of the later style of this engine — that 
fitted with automatic expansion gear, as here described — 
is probably about the same as that of other small engines 
of its own class ; not, as a matter of course, equal to the 
economy of large engines of the four-valve type, but great 
as compared with the class of small engines to which the 
manufacturer has usually been compelled to resort up to 
the present time, when demanding but little power. The 
loss by " friction of engine" is somewhat greater in 
this form than in the more familiar type of engine. The 






ELECTRIC LIGHTING PLANTS. 175 

peculiar advantages possessed by the engine in this di- 
rection are its high piston and rotative speed, and the 
extent to which compression is carried. One of these 
engines has been driven experimentally up to 2,700 revo- 
lutions per minute without any observable ill effect. 
Their speeds are probably safely made double that of the 
average "high-speed engine" with which we are now 
becoming familiar. Compression, as an element in eco- 
nomy of engine, has already been considered at some 
length. It was shown by the writer, ten years ago, that 
progress in the direction of improvement of the steam 
engine has always been retarded by the difficulty of pre- 
venting serious losses by cylinder condensation, and that 
this is the essential element of preventible waste ; it was 
also suggested by him, several years since, that probably 
the best means of controlling the speed of engine is by the 
introduction of high compression and its variation by 
the governor, increasing compression with increasing ex- 
pansion, and the reverse, and thus, by utilizing the heat of 
compression, checking cylinder condensation as its increase 
is caused by extending the expansion period ; and it was 
pointed out that " the best among existing forms of valve 
gear should, if judged by from the standpoint here taken, 
be that which, combining a variable expansion with a variable 
compression, is also capable of prompt and exact adjust- 
ment by a sensitive and efficient governor."* This sug- 
gestion, as has been seen, is fully met by all the later 
designers of engines of the high-speed class. The engine 

* Expansion of Steam, etc, Trans. Am. Soc. Mech. Engrs., 1881; Jour. Fran. 
Inst., Oct. 1881. 



176 STEAM ENGINES FOR 

above described illustrates well this use of compression; 
the compression is adjustable by the governor, and may 
thus given be that ratio which is best adapted to the case. 

Mr. Harris Tabor, in a paper read before the American 
Society of Mechanical Engineers, following the idea just 
presented, says of compression: "It is to the proper con- 
trol of compression that we must now look for further ad- 
vance in steam economy. ,, It has been seen that this is one 
of the directions of present advance. 



ELECTRIC LIGHTING PLANTS. 177 

VI. 

Latest Changes; the Compound Engine. 

TT 7E have now made a tolerably complete survey of the 
* * whole modern field of steam engineering as far as 
it is covered by stationary engine practice, and have seen a 
very steady progress from the best types of a generation ago 
to the most representative examples of the most modern 
forms It is seen that the direction of change is still that 
which, as has been often pointed out by the author, has 
been observed from the days of James Watt. The principal 
points found worthy of notice have been the increase in 
economy and general efficiency by a tentative and empirical, 
but none the less steady and uninterrupted, method of ad- 
vance. The pressures of steam have been slowly, but con- 
stantly, rising; speeds of piston, and of rotation, have been 
as constantly increasing; the effectiveness of the governor 
has been made greater and greater; the ratio of expansion 
at maximum efficiency has been very slowly increased, by 
the gradual reduction of " cylinder-condensation ;" commer- 
cial considerations have been brought definitely into view; 
the efficiency of engine has been improved by reduction of 
size, weight, and friction of engine; and thus we have been 
able to see a gradual change of type of engine effected, the 
engineer modifying his designs to meet the demands of the 
time, until we have insensibly, and almost without suspect- 
ing that progress has been going on, passed across a new 
line and entered upon an epoch, in steam-engine construc- 
tion, as marked in its period and as well defined, as to its 



173 STEAM ENGINES FOR 

beginning, as was that which, at the middle of the century, 
was distinguished by the introduction of the inventions of 
Sickles, Corliss, and Greene. 

The latest phase of this progress is to-day witnessed in 
the rapid introduction of the compound engine in all de- 
partments of electric work. There has been made, recently, 
a more careful study of the relative merits of the older 
" drop cut-off" engines and the modern " high-speed" 
type. This has led to the careful discrimination of the 
conditions under which each form of engine is advisable. 
The former, as constructed by the best makers, commonly 
excels in economy; the latter excels in compactness, cheap- 
ness, and in nicety of regulation. Where large power of 
uniform amount is demanded for considerable periods, 
without fluctuation or intermission, the older type is often 
the better; but, when the work is variable in amount, called 
for in irregular and uncertain periods, and capable at the 
same time of being divided among several engines, the later 
type is very generally advised. Thus it happens that both 
types of engine find constant employment and an increasing 
market. 

The most striking feature of current change is the intro- 
duction of the compound engine, and in both of these two 
principal classes of engine. A very large number of these 
engines with detachable valve-gear may now be seen at 
work where large " plants " are in operation, -and nearly 
every builder of the " high-speed automatic " engine is now 
" compounding " or preparing to compound his machine. 
The method and the serious importance of the wastes oc- 
curring in all heat-engines, in consequence of the impracti- 



ELECTRIC LIGHTING PLANTS, 179 

cability of constructing their working cylinders of a non- 
conducting substance, have already been stated. 1 

The unavoidable thermodynamic waste is rarely less than 
seventy-five or eighty per cent., and the internal wastes by 
conduction and storage, with subsequent rejection, by cyl- 
inder or internal condensation, as it is customarily called, 
and by leakage, range from ten per cent, as a minimum, 
perhaps, to twenty-five or thirty per cent., in good engines; 
to fifty per cent, in many cases, and even to much more 
than the latter proportion in exceptional cases. It is this 
which constitutes, ordinarily, the great source of loss and 
inefficiency of the real, as distinguished from the ideal, 
engine. 

The amelioration of wastes thus becomes an impor- 
tant matter. 2 The three methods which have been found 
advantageous, and, in special cases, fairly effective, are: 

(1.) Superheating ; 

(2.) Steam jacketing ; 

(3.) "Compounding." 

It is evident that, if the steam can be introduced into the 
engine at such a temperature that the cooling action of the 
metal of the cylinder will not cause its condensation initially, 
and the stroke may be performed without condensation in 
consequence of doing work, no loss of heat from the cylin- 
der can take place by re-evaporation; and if no such loss 
occurs, the waste of heat at entrance, in turn, by initial 
cooling, will be reduced. Superheated steam, also, is a 

1. Chapter II., p. 9. 

2. This portion of this chapter is mainly condensed from a paper by the 
author, read before the American Society of Mechanical Engineers, November, 



180 STEAM ENGINES FOR 

non-conductor and a non -absorbent of heat, precisely like 
the permanent gases. It is thus, also, less liable to this 
waste. But it is found in practice that superheating be- 
yond a very moderate degree, perhaps iooto 150 degrees 
Fahrenheit, is inadvisable on account of risks of injury to 
engines and cost of repairs to superheater, which more than 
compensate its advantages. 

Steam-jacketing is another and a common partial remedy 
for this waste. By surrounding the steam-cylinder with the 
steam-jacket, it is possible to produce, in part, the effect of 
superheating; that is, to secure dryer steam in the engine 
throughout the stroke. The amount of re-evaporation, dur- 
ing the period succeeding cut-off and up to the closure of 
the exhaust-valve, and the quantity cf heat of which the 
cylinder is thus robbed, measures the amount of initial con- 
densation and waste, and the weight of steam which must be 
supplied in excess of the thermodynamic demand to com- 
pensate that loss. The effect of the addition of a steam- 
jacket depends upon the conditions of operation of the 
engines, largely, and may be productive of marked advan- 
tage, or, under unfavorable conditions, of no important use- 
ful effect. High-speed engines derive less advantage from 
its application than slow-moving machines; and compound, 
or multi-cylinder, engines are less dependent upon it for 
economy than are simple engines. The addition of this 
expedient, if properly performed, appreciably increases the 
magnitude of the ratio of expansion at maximum efficiency 
of fluid. The assumption is commonly made that the 
superheating is retained throughout the stroke, and that 
steam-jacketing may be relied upon to keep the working 






ELECTRIC LIGHTING PLANTS. 181 

charge dry and saturated throughout the stroke; but neither 
of these hypotheses, as employed in the theory of the engine, 
is probably, as a rule, practically correct. 

"Compounding" 'or the use of the multiple-cylinder engine, 
in which the steam exhausted from one cylinder is again 
worked in a succeeding one, is the most familiar of devices 
for extending the economical range of expansion and in- 
creasing the efficiency of the engine. The limit to the 
useful extension of the expansion of steam in a single cylin- 
der is found to be determined by the magnitude of the 
wastes incurred in the operation of an engine of which 
the working cylinder is a good conducting material. Any 
method of reducing this waste of heat internally will enable 
the efficiency of the engine to be increased by further 
profitable extension of the ratio of expansion. Common 
experience with the best constructions, and considerations 
which need not be here reviewed, show that the engineer 
may reasonably expect, by good design, construction, and 
management, to secure an economy of steam which is fairly 
measured by the following table, the ratios of expansion, r, 
taken being, for each case, those which give best results for 
a given engine, engines of fair size being taken : l 

Steam per Horse-power per Hour, 
At best ratios of expansion in best engines. 

r 3 4 5 6 7 8 io 12 15 20 25 50 75 
lbs. 32 27 25 22 20 20 19 17 16 15 15 1.1 0.9 
kgs. 15 12 11 11 9 9 9 8 7 7 7 05 04 



1. Several Efficiencies of the Steam Engine ; Trans. A, S, M. E., and Jour. 
Franklin Inst., 1882, 



1 82 STEAM ENGINES EOR 

and ten per cent, better figures than these have been actu- 
ally reported in peculiarly favorable cases. 

Assuming it to be possible to divide the waste by cylinder 
condensation and leakage by two or more, it is evident that 
the limit to economical expansion and transformation of 
heat into work will be set correspondingly further away. 
This is precisely what is done by the multi-cylinder engine. 
The internal wastes are reduced approximately to those of 
the most wasteful single cylinder, and the gross percentage 
of waste is made less in the proportion of this division. 
The heat and steam rejected as waste by internal transfer 
without transformation from the first cylinder, is utilized in 
the second nearly as effectively as if it were received directly 
from a boiler at the pressure of rejection from the first cyl- 
inder. Insomuch, therefore, as the pressure can be in- 
creased and the increase utilized by the addition of another 
cylinder, gain is secured. 

The practical questions thus meet the engineer : To 
what extent can this principle be availed of ? what range 
of pressure and what ratio of expansion should be assigned 
to a single cylinder ? and how many cylinders should be 
adopted to give best results with the highest steam pres- 
sure practicable for a specified case ? Common experience 
aids in solving this problem by showing that the very best 
results are ordinarily obtained, in each class of multi- 
cylinder engine, when, the engine being properly designed 
for its work, terminal pressure for the system can be eco- 
nomically made something above the sum of back pressure 
in the low-pressure cylinder, plus friction of engine. This 
total may be usually taken as a maximum, probably, at 



ELECTRIC LIGHTING PLANTS, 183 

about eight or ten pounds above a vacuum. The latter 
figure will be here assumed. 

The Fundamental Principles are now easily per- 
ceived. There are three main facts upon which to base 
our theory of the multi-cylinder engine. These are : 

(1.) Economical expansion in a single cylinder has a limit, 
due to increasing inte7'nal wastes, which is found at a com- 
paratively low ratio of expansio?i. 

(2.) The method of expansion maybe, for practical pur- 
poses such as are here in view, taken to be approximately 
hyperbolic j the terminal pressure being something above that 
which corresponds to the sum of all useless resistances, and 
which may be here taken, as, for example, about ten pounds 
per square inch above a vacuum. The division of the initial 
pressure by this terminal pressure will thus give an approxi- 
mate measure of the desirable ratio of total expansion for 
the best existing engines. 

(3.) All steam entering any one cylinder will be rejected, as 
steam, 1 into the succeeding cylinder, external wastes being 
neglected, and into the condenser ; and the full amount of 
steam condensed at entrance by absorption of heat by the in- 
terior surfaces of the cylinder will be re-evaporated later, 
and will pass into the condenser or into the next cylinder ; 
and heat transferred in the one direction, in the one process, 
will be transferred in precisely equal amount in the opposite 
direction in the other. 

This last point is a very important one, and is very easily 
established. The cylinder, when in steady operation, is 

t. This the author would denominate Hirn's principle. See a paper by M. 
Dwelshauvers-DeYy in he Bulletin de la Societe Industrielle de Mulhouse, Octo- 
ber, 1888, on the theory of single-cylinder engine. 



1 84 STEAM ENGINES FOR 

neither permanently heated nor permanently cooled ; no 
progressive heating can go on, as it would, in that case, 
become heated above the temperature of the steam and 
become a superheater ; no progressive cooling can occur, 
since, in that case, the cylinder would become a condenser 
of indefinite capacity. It must, therefore, transfer to the 
next element of the system all the heat which it receives, 
assuming that external radiation and conduction may be 
neglected, and that the Rankin e and Clausius phenomenon 
of internal condensation, by transformation of heat into 
work, is ignored. It also further follows that the introduc- 
tion of one or of many cylinders between the terminal ele- 
ment and the boiler does not, through cylinder-condensation 
alone, affect the operation of the latter cylinder, however 
great that condensation may be ; provided the operation of 
the added elements is effected by raising the steam pressure 
commensurately, leaving the final element of the series the 
same initial pressure as before. The total waste by this 
form of loss is thus evidently measured, in the case of the 
multi-cylinder engine, by the maximum waste in any one 
cylinder. If all are equally subject to this loss, the rejected 
steam of re-evaporation from any one cylinder, as the high- 
pressure cylinder, supplies precisely what is needed to meet 
the waste by initial condensation in the next ; and so on 
through the series. Thus the use of a series of cylinders, 
in this manner, divides the total waste for a single cylinder, 
approximately, at least, by the number of cylinders ; and it 
is in this manner that the compound system gives its remark- 
able increase of efficiency. As stated by the author, many 
years ago, " The serious losses arising from condensation 



ELECTRIC LIGHTING PLANTS. 185 

and re-evaporation within the cylinder, and which place an 
early limit to the benefit derivable from expansion, affect 
both types of engine, and so far as seems now known, 
equally ; " ' but the compound type permits the intercep- 
tion of the heat wasted from one cylinder, for utilization by 
its successor, in such manner that the total waste becomes, 
practically, that of the low-pressure cylinder alone. If any 
one cylinder wastes more than another, the total waste is, 
as above stated, measured more nearly by the loss in the 
most wasteful member of the system. 

Thus the three principles which have been above enun- 
ciated give a means of constructing a philosophy of the multi- 
cylinder engine, which will meet the essential needs of the 
designer and of the student of its theory. The first principle 
shows that, a limit existing to economical expansion in a 
single cylinder, the advisable number of cylinders in series 
may probably be determined, when that limit is ascertained, 
either by experiment, by general experience, or by rational 
theory and computation. The second principle shows that 
we may find a tentative measure, at least, of the desirable total 
ratio of expansion for maximum efficiency, when the best 
terminal pressure for the chosen type of engine is settled 
upon. This total range is divided by the admissible range 
for a single cylinder ; or, perhaps better stated, the total 
ratio is a quantity which should approximately equal the 
admissible ratio for a single cylinder, raised to a power de- 
noted by the number of cylinders. Combining thus the 
two considerations referred to, we obtain a determination, 
probably fairly approximate, of the proper number of cylin- 

1. Vienna Report, 1873. 



1 86 STEAM ENGINES FOR 

ders in series. The third principle permits an estimate to 
be made of the probable internal wastes of the series, and 
the probable total expenditure of heat and of steam, and a 
solution of all problems of efficiency for the compound 
engine, of whatever type. 

The first step in the process is evidently the determination 
of the best ratio of expansion, under the assumed conditions 
of operation and for the given type of engine, for a single 
cylinder ; then the best ratio of expansion for the series, all 
things considered ; this study being made from the financial 
standpoint, as must be every problem which the engineer is 
called upon to solve. It is not the thermodynamic, nor the 
fluid, nor even the engine, efficiency, which must be finally 
allowed to fix the best ratio of expansion ; but it must be 
the ratio of expansion at maximum commercial efficiency ; 
that which will make the cost of operation at the desired 
power a minimum for the life of the system. 1 The total 
ratio being settled upon, and that allowable, as a maximum, 
for the single cylinder, it is at once easy to determine the 
best number of cylinders in series. The first-mentioned 
ratio is that at maximum commercial efficiency, as just 
stated ; but the second must be taken as that which gives 
the highest efficiency of engine ; the back-pressure in that 
cylinder, and the friction of the cylinder, taken singly, being 
considered, together with its proper proportion of the friction 
of the engine as a whole. 

The extent to which expansion may be economically car- 
ried in a single cylinder will vary somewhat with the initial 

i. See papers by the author, on the efficiencies of engines, as per references 
already given. 



ELECTRIC LIGHTING PLANTS, 187 

temperature and pressure, and with the physical condition 
of the working fluid ; but it may be taken as ordinarily not 
less than two-and-a-half expansions for unjacketed engines 
with wet steam, and three or four for the better class of 
engines. The total expansion ratio thus becomes, for sev- 
eral types of multi-cylinder engines, as below : 

MULTI-CYLINDER ENGINES. 

No. cyls. 1 2 3 4 

r 2.5 to 3 6.25 to 9 16 to 27 40 to 81 

pi 25 to 30 lbs. 60 to 100 lbs. 120 to 300 lbs. 350 to 800 lbs. 

Expansion is here assumed to be approximately hyperbolic, 
and the terminal pressure to be eight or ten pounds per 
square inch. General experience to date thus indicates 
that a triple expansion engine should do best work up to a 
pressure of about p x — 250 or 300 pounds, and that the four- 
cylinder engine should be adopted from that point up to the 
highest pressures likely to be adopted in the steam engine, 
the double expansion compound serving its purpose well 
below the lowest figures above assigned to the triple engine. 
Any of the four types of engine may be made to overlap the 
range assigned that case by suitably providing against wastes 
occurring within the engine by increased speed, by super- 
heating, by expedients giving higher effectiveness to the 
jackets, or other* methods of improvement. Any system 
which increases the efficiency of the simple engine will im- 
prove the efficiency of the compound, and will correspond- 
ingly increase the range of pressure through which it will 
give satisfactory gain as compared with the former. 

The influence of the several economical expedients rec- 



1 88 STEAM ENGINES FOR 

ognized as useful in other forms of engine, such as super- 
heating, jacketing, and high speed of engine, may readily 
be perceived when the method of operation of the multi- 
cylinder engine is understood in its relations to heat-trans- 
fer and heat-transformation. We may consider them in 
their order : — 

Superheating the steam transferred from boiler to en- 
gine results in the supply of a fluid which may surrender a 
certain portion of heat, measured by the product of its spe- 
cific heat as a gas into the range of superheating and into 
its weight, to the metal of the working cylinder without the 
production of initial condensation. If this quantity is equal 
to or greater than the loss of heat during expansion and ex- 
haust, there will be no initial condensation, and the waste 
from the high-pressure cylinder will be nearly that due to 
the passage of a gas through it under similar conditions of 
temperature and expansion, a comparatively small quantity, 
since any substance in the gaseous state possesses low con- 
ductivity and slight power of absorption and storage of 
heat. Should the superheating be in excess of this amount, 
the steam will not begin to condense until a later period, 
perhaps not at all, the only demand being now for heat 
to supply the amount required to keep the steam dry and 
saturated while expanding and doing work. If the super- 
heating be less than the first - mentioned quantity, ini- 
tial condensation will be reduced, but not entirely pre- 
vented. In any case, the quantity of heat represented by 
the superheating will be a gauge of the amelioration of 
wastes by internal transfer of heat in every cylinder of 
the series. The steam leaving the high-pressure cylinder 



ELECTRIC LIGHTING PLANTS. 189 

will be to that extent dryer than it would otherwise be ; 
and this will be true of the succeeding cylinder or cylin- 
ders. 

Were there no other disappearance of heat than that due 
to cylinder condensation, superheating at the first of the 
series would give superheating at each of the others. In so 
far as condensation doing work, such as was pointed out by 
Rankine and Clausius, takes effect, and so far as other 
wastes by transfer without transformation occur, to that ex- 
tent will the gain, as observed in successive passages from 
cylinder to cylinder, be reduced ; though the improvement 
of the working conditions above asserted will be none the 
less real. Each cylinder will have wetter steam than the 
preceding, in proportion as the condensation doing work 
and the losses by conduction and radiation increase, as a 
total, cylinder by cylinder. 

Steam jacketing, the expedient devised by James 
Watt, for the very purpose of reducing wastes by internal 
condensation, a phenomenon of which he was the discov- 
erer, is a method of approximately " keeping the cylinder as 
hot as the steam which enters it," as Watt put it, in order 
that no such chilling of the entering steam may occur. We 
are interested in the answer to the question: To what extent 
and in what manner is the jacket advantageous in the com- 
pound or multi-cylinder engine ? Authorities disagree, even 
where they have themselves had large practical experience. 
It is sometimes advised to jacket only the high-pressure 
cylinder; sometimes to jacket only the low-pressure cylin- 
der, and sometimes to jacket the whole series, whether one, 
two, or three or more. The philosophy of the multi-cylin- 



190 STEAM ENGINES FOR 



. 



der engine, as above outlined, would obviously indicate 
that, to secure maximum good effect, assuming the jacket 
on the whole desirable at all, the best system is the lat- 
ter, and that, since the waste of the engine is measured 
by the waste of its most wasteful member, to omit the jacket 
from any one cylinder insures tljat the aggregate loss of heat 
in the whole engine will be increased by just the amount by 
which waste is increased in that one cylinder by such omis- 
sion. 

It is readily seen, however, that, to secure maximum effi- 
ciency, it is as essential to jacket the cylinders of the com- 
pounded engine as that of the simple engine. The question 
which actually arises in practice, for the designing engineer, 
is whether it will pay to jacket at all or not. It can at 
once be seen that it is not as important, in a financial 
sense, that the multi-cylinder engine be jacketed as it is 
to jacket a simple engine of similar range of expansion. 
The value of the waste due to omission of the jacket is 
less as the number of cylinders is the greater, and is the 
less on any one cylinder as the expansion in that cylinder 
is a less proportion of the whole. It is also seen that 
those conditions which may make it undesirable, as a mat- 
ter of finance, to jacket the simple cylinder, make it still 
less desirable in the compound or multi-cylinder engine. 
As piston speeds are increased, for example, the necessity 
of the jacket decreases and the limit at which it will pay 
to dispense with it is sooner reached in the multi-cylinder 
than in the single-cylinder engine. It is this principle 
which justifies the now not uncommon practice of omit- 
ting jackets from marine engines which are driven up to 



ELECTRIC LIGHTING PLANTS. 101 

1,000 feet a minute; while pumping engines, in which the 
speed is always very low, must usually be jacketed if high 
duty is demanded. 

High engine-speed, the most modern device for reduc- 
ing internal wastes, as well as for decreasing costs of engine 
construction and weights of machine, is evidently a mat- 
ter of less serious importance as the number of cylinders 
is increased; yet it is equally evident that, to secure max- 
imum efficiency, it is essential that the time of exposure 
to the action of the wasteful influences in any one cylin- 
der be made a minimum. At modern and customary 
speeds of piston and of rotation, the value of this, as well 
as the other expedients for improving performance, is much 
less than formerly. 

Non-conducting cylinders, such as were partly se- 
cured by Smeaton by the use of his wood-lined pistons 
and heads, and such as have since been sought by Emery 
and others ; such as was shown to be needed by Watt, 
and later more conclusively by Rankine and his successors; 
would do away with the necessity of compounding on the 
ground of thermodynamic gain ; but would leave the ad- 
vantages of the multi-cylinder engine, on the score of bet- 
ter division of stresses and work, unaffected. What may 
be done in this direction, it is as yet impossible to judge; 
but it is not likely that the device of Smeaton can be made 
successful at modern temperatures and pressures, or in pres- 
ence of superheating; the plan of Emery of using glass, 
enamel, or other superficial covering of the exposed sur- 
faces, has not yet given promise of success, and nothing as 
yet tried seems to give promise of meeting the requirements 



192 STEAM ENGINES FOR 

of the case. 1 The value of even an approximately non- 
conducting covering of such nature would be considerable 
for the compound engine, and very great for the simple 
engine; especially for the smaller sizes in which the pro- 
portion of exposed surface is comparatively large. 

Conclusions would thus seem justified as follow : Under 
similarly favorable conditions we may, with equal likelihood, 
anticipate a probability that we may obtain better work with 
multi-cylinder engines in somewhere about the following 
proportion for good examples : 

Gain, Gain, 
Engine. Steam Consumption. Total. Diff. 

Small Lar ^e 

Engines. Engines. 

Simple i-cylinder Per I. H. P. 40 lbs. per hr. 20 lbs. 

Compound (double expansion). 30 16 20% 20% 

Triple expansion 20 14 30 10 

Quadruple expansion 18 12 40 10 

Quintuple expansion 16 n 50 10 

The first three cases are based upon what is probably 
ample experience ; the last two are obtained by inference 
from the rate of progression thus established, checked by 
computation, assuming that the loss is reduced in propor- 
tion, approximately, to the number of cylinders in series. 
The probable cost of adding one and another cylinder to 
any given type is easily ascertained by the engineer ; he 
knows the cost of fuel and oil ; the value of capital is as 
easily ascertained ; and he can then readily determine 
whether the gain fairly to be anticipated is sufficient to 

1. The author has recently secured an invention devised by himself, consisting 
in the solution of the exposed metal surfaces, leaving the carbon of the casting to 
form a layer resembling vulcanized rubber, which is to be saturated by drying 
oils, solutions of gum or other non-conductor, the covering so formed being inte- 
gral with the cylinder-head or other part. 



ELECTRIC LIGHTING PLANTS, 193 

compensate the cost of its acquirement and to give a fair 
margin of profit. 

Another important inference from what has preceded is 
that the question of use of one or another type of multi- 
cylinder engine is not primarily settled by the magnitude of 
the steam pressure to be adopted ; although it is well settled 
by experience and by the financial aspect of the question, 
as just indicated, that it will not pay to compound a machine 
working at very low pressures ; nor to adopt a third cylinder 
until the pressure approaches, perhaps, four or five atmos- 
pheres, the advisability of adding cylinder after cylinder 
being measured by the rise in pressure, at the rate of not 
more than one cylinder for each four or five atmospheres 
pressures. Whatever the pressure, however, the compound- 
ing will divide the total thermal loss by internal wastes, ap- 
proximately, by the number in series ; but it does not at all 
follow that the efficiency of engine or the commercial effi- 
ciency will be reduced in similar ratio. On the contrary, it 
will never pay to carry the complication as far as the study 
of the ideal case would dictate. The discrepancy will be 
found to be the greater as the real engine the more closely 
approaches ideal perfection, the simple engine becoming the 
more desirable type as the efficiency of it and of each of the 
several elements of the compound engine becomes greater. 

As respects size, it is now easily seen that the gain by com- 
pounding is, so far as the considerations here studied are 
concerned, at least, likely to prove even more marked with 
small than with large engines; although it may not be, 
commercially, as desirable to adopt this complication. As 

the wastes are invariably, under similar working conditions, 
13 



194 STEAM ENGINES FOR 

greater as size decreases, the desirability of reducing the 
magnitude of those losses would seern likely ordinarily to 
be made the greater, also, as size of engine diminishes. 
With equally dry steam from the boiler, the moisture in the 
steam and the losses by internal condensation are the larger 
as the power supplied and the magnitude of the engine 
furnishing it become less. That experience is showing this 
to be the fact is evidenced by the steady progress made by 
builders of small engines in the introduction of the com- 
pound engine into the market. In the case of the adapta- 
tion of this system to small engines, the effect of cylinder 
condensation remains in each cylinder, well marked, ordi- 
narily, as is seen in the hitherto unnoticed effect observable 
where such small engines are constructed of the Wolff type ; 
and the first effect of the cooling action of the metal upon 
the entering steam is shown by the sudden drop of pressure 
between the two cylinders, at the moment of opening com- 
munication, the fall being like that seen when exhaust 
occurs into the atmosphere from a high terminal expansion, 
and amounting, often, to several pounds. 1 

Problems relating to the efficiency of the multi- 
cylinder engines may be solved most simply by the processes 
devised by the author in modification of the method of 
Rankine, originally applied to the study of the ratio of ex- 
pansion at highest efficiency of capital. 2 The number of 
cylinders or of grades of expansion being in all such cases 
settled by general experience and the judgment of the de- 



i. This has been noticed and provided for by the designers of the familiar type 
of single-acting compound. 
2. Miscellaneous Papers. 



I 



ELECTRIC LIGHTING PLANTS, 195 

signing engineer, the best ratio of expansion and the best 
proportions of cylinders are readily determined for any 
given case by first obtaining the true Curve of Efficiency 
for the given class of engines, and then, knowing the prob- 
able back-pressure to be met with, either by custom or by 
taking it with reference to the best relation of initial to final 
pressure, and computing the constant and variable costs of 
operation, solving the problems, in their proper order, by 
a graphical construction which the author has shown to be 
easy and accurately made. 1 It is enough to say here that 
these best ratios will often be found, for the better class of 
engines employing dry or slightly moist steam, to be not far 
from one-half the ratio of initial to back-pressure, the latter 
including the friction of engine ; and for those of the very 
highest class, using thoroughly dry or superheated and re- 
heated steam, on the system adopted by Cowper, Corliss, 
and Leavitt, this best ratio may be raised economically, on 
the whole, to about two-thirds the ratio of initial to back- 
pressure. 

It is safer, however, to endeavor to find the real curve of 
efficiency for the class of engine considered, and use that 
curve in the solution of the problems of the efficiency of 
fluid, of efficiency of engine, and of efficiency of plant. It 
thus becomes easy to ascertain the best ratios for highest 
duty, for best financial results as designed, as for best 
commercial returns should the opportunity offer of utilizing 
more power than is at first anticipated. 

Proportions of cylinders and relative ratios of 

1. The Several Efficiencies of the Steam Engine. Jour. Franklin Institute, 
May, 1882. 



196 STEAM ENGINES FOR 

expansion in the several cylinders of the multi-cylinder 
engine may readily be settled when the total ratio and the 
total power demanded are determined and exactly pre- 
scribed. It will be found that the total ratio will be made, 
usually, not far from equality in the several cylinders, and 

r = r t n ; 

where n is the number of cylinders adopted, r the total ratio, 
and r x the ratio for one cylinder. It will, however, for best 
effect, on the whole, be properly advisable to adopt a com- 
promise between the various modified and conflicting values 
prescribed by the conditions that the work, the effective ini- 
tial pressures, and the several products of range of tem- 
perature into exposed areas, shall be as nearly equal in all 
cylinders as possible. To meet the first condition we must 
have such a ratio in each cylinder as shall make the work 
in each equal to the total net power of the engine divided 
by the number of cylinders in series ; to meet the second 
condition we must make the initial pressure in each such 
that the total range of pressure may be equal to a common 
range in each multiplied by the number of cylinders ; while 
to make the stated products equal throughout the series 
we must have varying differences of pressure, the high- 
pressure cylinder having the maximum range, and the low- 
pressure cylinder the minimum range of pressure. The dif- 
ferences in this latter respect are, in engines using very 
high steam-pressures, quite considerable. Where the steam 
is dry, the speed of engine high, and the jacketing effective, 
this is a matter of less consequence than approximately 
uniform division of work and stresses on the crank-pins. 






ELECTRIC LIGHTING PLANTS, 197 

It is by the application of the principles which have been 
so fully described above that the steam engine for electric 
lighting purposes has been of late so greatly improved in 
respect to its economy of fuel and steam. The gain by 
compounding the smaller engines is so much greater than 
with the larger and originally more economical simple 
engines, that the disadvantage under which the high-speed 
engine has in some respects labored is to a considerable 
extent removed ; and, among compound engines, all the 
common types are more closely competitive. All are ap° 
proaching more and more a common ideal. 



INDEX TO ADVERTISERS IN THE ORDER 
THEY APPEAR. 



The Armington & Sims Engine Co. 

Edw. P. Allis & Co. 

The Lane & Bodley Co. 

Southwark Foundry and Machine Co. 

Providence Steam Engine Co. 

Holmes, Booth & Haydens. 

The Westinghouse Machine Co. 

Benj. F. Kelley, Agent. 

John Wiley & Sons. 

William A. Harris. 

The Deane Steam Pump Co. 

The Edson Recording and Alarm Gauge Co„ 



THE ARMINGTON & SIMS' 

Automatic Cut-off Engine, 

For all purposes where power is required. 




CLOSE REGULATION. ECONOMY OF FUEL 

SMALL SPACE REQUIRED. MODERATE PRICE. 

OVER 1,700 ENGINES IN USE. 

BUILT BY 

The Armington & Sims Engine Co., 

PROVIDENCE, R.I. 



ESTABLISHED 1853. 



IjOLIjES, BOOTI-J & HAYDENS, 



MANUFACTURERS OF 



HARD DRAWN COPPER LINE WIRE 



TELEGRAPH AND TELEPHONE, 

Pat. Insulated Electric Light Wire, 

MAGNET WIRE , 

Patent "KK" Insulated Copper and Iron Wire, 

RED AND WHITE INSULATED IRON LINE 
WIRE, ETC., ETC. 



NEW YORK. BOSTON. PHILADELPHIA. 

FACTORIES I 

WATERBURY, CONNECTICUT. 




THE 



Westinghouse Automatic Engine, 

THE MOST POPULAR ENGINE IN THE MARKET FOR 

ELECTRIC LIGHTING 



ON THE 



System of Independent Power. 

SEND FOR ILLUSTRATED CIRCULAR, AND SPECIAL CIRCULAR 
ON ELECTRIC LIGHTING. 



The WESTINGHOUSE MACHINE CO., PITTSBURGH, PA. 



SALES ROOMS: 



94, LIBERTY STREET, NEW YORK. 

4,01 ELM STREET, DALLAS, TEXAS. 

401 COLLEGE STREET, CHARLOTTE, N. C. 

53 S. MARKET STREET, NASHVILLE, TENN. 

FAIRBANKS, MORSE 6c CO., CHICAGO, ILL. 



EDW. P. ALLIS & CO., 

DE WORKS, - MILWAUK1 

Manufacturers of the 

REYNOLDS 1 IMPROVED CORLISS ENGINE. 



RELIANCE WORKS, - MILWAUKEE, WIS.,, 

Manufacturers of the 




PURPOSES. 



UNEQUALED 

FOR CLOSE 
REGULATION 
AND ECONOMY 
OF FUEL. 



600 of these Engines of 200 horse power and adovp now In use. 

We refer to the following well-known Electric Lighting Companies and Firms having our engines 

now in use : 



Brush Electric Light and Power Co.. Cleveland, O. 



Badger Illuminating Co.. Milwaukee, Wis. 
J. V. Farwell & Co., Chicago, 111. 
Mandel Bros., Chicago, 111. 
Sherman House, Chicago, 111. 
West Hotel, Minneapolis, Minn. 
Plankinton House, Milwaukee, Wis. 
Menominee Mining Co., Iron Mountain, Mich. 



West Side Power Co., Minneapolis, Minn. 
Louisville Electric Light Co , Louisville, Ky. 
Edison Electric Light and Power Co., Rockford, 111 . 
La Crosse Brush Electric Light and Power Co., 

La Crosse, Wis. 
Chicago, Milwauke & St. Paul Railway Co. 

BRANCHES: 
PACIFIC SLOPE : Cor. 1st and Mission Sts., San Francisco, Cal. CHICAGO : 48 S. Canal Street. 
Eastern Representatives : Westinghouse, Chuech, Keek & Co., No. 17 Cortlandt St., N. Y. City. 

The LANE & BODLEY CO. 




MANUFACTURERS OF 



The Improved Corliss Engine 

Of Modern Design, Liberal Proportions. 

Unrivaled for Durability, Ggonomy and FJegulaiuon 



Most Satisfactory Power for Electric Lighting. 

Complete Power Plant a Specialty. 

Shafting, Hangers, etc., of Best Construction. 

We arrange to disconnect Dynamos without clutches or loose pulleys. 
THE LANE & BODLEY CO., Cincinnati, O. 



SOUTHWARK FOUNDRY 



AND 



MACHINE COMPANY, 

Washington Ave. and Fifth Street, Philadelphia, Penr. 

Porter-Allen and Southwark Engines. 

BOILERS AND TANKS. 

BESSEMER PLANTS. WATERWORKS PUMPS. 

HYDRAULIC MACHINERY. GAS APPARATUS. 

HEAVY CASTINGS. MACHINE WORK. 

ELEVATORS. SUGAR MACHINERY, Etc. 

REMEMBER 

THAT THE 

Improved Green Engine 

Is the ONLY Cut-off Engine with Liberating Valve Gear 

Without Springs, Catches, or Wedges, 

Thus relieving the governor of 

All Strain While Tripping. 

By a recent change we dispense with springs on tappets. 



PROVIDENCE STEAM ENGINE 60., 

Providence, Rhode Island, 

SOLE BUILDERS. 

H. W. GARDNER, T. W. PHILLIPS, 

Pres't and. Treas. Secretary. 




THE BERRYMAN 




BENJ. F. KELLEY,. Agent, 
No. 91 Liberty Street, - New York. 



This Heater is firmly established, and has received 
the unqualified approval of mechanical engineers 
throughout the United States. 

HAS SEAMLESS DRAWN BRASS TUBES. 

The U shape prevents their being affected by expansion 

or contraction. It lias been in constant use over twelve 

lyears. None have ever required repairs. Gives the 

-'-highest results attainable by the use of exhaust steam. 

•4 Prices made known on application. Give size or 

horse-power of boilers, size of engine and diameter of 

exhaust pipe. 



ISTOTJV REA3DY. 



ELECTRIC .-. ILLUMINATION 

GENERAL PRINCIPLES, CURRENT GENERATORS, 
CONDUCTORS, CARBONS AND LAMPS. 



JAMES DREDGE. 
S. P. THOMPSON. 



Chiefly compiled from "Engineering. 

BY 

CONRAD W. COOKE. 

EDITED BY 

JAMES DREDGE. 



M. F. O'REILLY. 
H, VIVAREZ. 



With Abstracts of the Specifications deposited at the Patent 
Office, between 1837 and 1872, having reference to Electric 
Lighting. Prepared by Mr. W. LLOYD WISE. 

Quarto, 900 pages, with nearly 806 Illustrations. Cloth. $7.50. 

JOHN WILEY & SONS, Astor Place, New York, 

Publishers of Scientific and Industrial Works. 

Vol. II. ready in October, comprising Installations, Motive Power, 
Cost of Production and Maintenance, Electrical Photometry, 
Secondary Batteries, Accessories to Electric Lighting, etc., etc. 
Together with the completion of the Patent Abridgments, from 1872 to 
1882. Each volume will be sold separately. 



THE HARRIS-CORLISS 

STEAM ENGINE. 




BUILT BY 

WILLIAM A. HARRIS, 

PROVIDENCE, R. I., 

From 10 to 2000 Horse Power, - 

WITH HARRIS IMPROVEMENTS. 

These Engines are of Unexcelled Workmanship, and are known the 
world over as the Most Economical Steam Engines Built. 



ELECTRIC LIGHT COMPANIES TAKE NOTICE. 

Xhey are specially adapted for all purposes where 
CONTINUOUS SERVICE AT UNIFORM SPEED IS 
REQUIRED, AND AT THE MINIMUM OF COST OF 
REPAIRS. 



Send for a copy of Engineers' and Steam Users' Manual, 
by J. W. HILL, M.E. Price, $1.25. 



Tp Deane Patent Stem Puijps. 

FOR EVERY POSSIBLE SERVICE. 

SIMPLE IN CONSTRUCTION, CERTAIN IN ACTION, 
BEST MATERIAL AND WORKMANSHIP. 




11 o. 3 Pump, with Hand Lever. 

THE DEANE BOILER FEED PUMPS 

•sxre positive at all speeds and pressures. Arranged for hot or cold 

water. 




Complete Independent Air Pump and Condenser. 

i'FJE DEpE CONDENSER FOR STEAM ENGINES 

effects a marked increase of power, or saving of steam. Illustrated catalogue and 
other information on application to 

THE DEANE STEAM PUMP COMPANY, 

HOLYOKE, MASS. 



-Ht EDSON'S-ls* 



Life Saying and other 




THE EDSON RECORDING AND ALARM GAUGES 

furnish written " Charts" in a permanent form, of the Speed of Machinery, 
or, of the Pressure of Steam, Air, or Water within any boiler, pipe or 
reservoir. 

The record is a continuous line or tracing made upon a ribbon of paper, 
graduated by horizontal lines, into a scale of pressure, and by vertical lines 
to a scale of time or of distance, or rate of speed or motion. 




The " Chart " is moved by a Chronometer which is exactly regulated 
and especially adapted to its work. Ordinary speed, % inch and 1 inch 
per hour (nearly). The portion of " Chart " traced upon should be critically 
examined daily, or oftener, and then it should be filed away for future 
reference, regarding the skill and fidelity of the fireman, or engineer, the 
character and efficiency of work done, and whether human lives are carefully 
guarded, and all lawful requirements for securing safety complied with. This 
Instrument was adopted and used as the only correct Recording and Indi- 
cating Gauge, by the Franklin Institute Experts appointed to establish a 
Bureau of "Standards of Pressure " at the late International Electrical 
Exhibition in Philadelphia, Pa. These Instruments supply legal evidencein 
many cases of inestimable value. They were used by Prof. R. H. Thurston 



and his associates during the celebrated Steam Boiler trials at the American 
Institute, N. Y., in 1871, and by the Judges at the Centennial Exhibition at 
Philadelphia, 1876. It is still used by the Mechanical Laboratory of the 
Stevens' Institute of Technology for its experimental work, and by its 
Director in private work. It is used by the Brooklyn Bridge Co., by the 
great lines of Atlantic Steamers, by the Public Works Departments of the 
principal cities of the United States, by the Electric Light Companies, the 
great Gas Companies, and by hundreds of private establishments throughout 
the country. It has been adopted by the Supervising Architect of the 
United States for use in the Public Buildings in his Department. Once in 
use, it is always found indispensable to comfort, convenience and safety. 




The simplicity of these instruments and their accuracy are important 
recommendations, while the assurance which they give against dangerous 
or costly accidents justifies fully the small expense of their purchase. 

An Alarm Gong is added to give notice of overpressure, and thus to 
secure instant attention. 

' ' E&son's Electro- Magnetic Alarm Apparatus " is furnished at small 
additional cost, where notice of approaching danger is to be given at a 
distance, or to different parties. 




VIBRATING ALARM GONG AND 

BATTERIES. 
To be placed in Engine Room or 

elsewhere. 



The "Alarms" are arranged for "low pressure," or for high-pressure' 
limit, as shall be ordered. 

These instruments, being absolutely automatic, give testimony that is 
never doubted, and do their work with perfect certainty and invariable 
exactness. They never forget and never make a mistake. A pointer and 
dial give the same indications as are seen on the old form of indicating 
gauges, and permit ready reading of the pressure at any instant without 
reference to the chart, while, at the same time, enabling the latter to be 
standardized conveniently. 



EDSOH'S SPEED AND PRESSURE RECORDING GAUGE. 




This Instrument gives records simultaneously of the steam or wate 
pressure and of the speed of engines or machinery. Both are recorde 
upon the same chart, continuously and accurately. 

The width of the loops in above tracing (lower line) indicate the leng 
of time the speed was interrupted — as of a train of cars — and between what 
s^tions, and whether unlawful speed was afterwards resorted to, in recover- 
ing the lost time or opportunity. 

Perfection in electric lighting cannot be reached until uniformity shar 
bo secured ; hence, Dynamo Engines must be automatically watched, and 
data obtained and preserved for comparisons of work performed and results 
obtained from time to time. 

Full instructions for unpacking, setting up and running always 
sent with instrument. 

For Illustrated Pamphlets, Specimen Charts, Prices, or further in- 
formation and reference to patrons, etc. , apply to 

THE EDSON RECORDING AND ALARM GAUGE CO., Proprietors, 
No. 91 Liberty Street, New York. 



M- B. EDSON, President. 



